US President Donald Trump and French President Emmanuel Macron hold a joint press conference at the White House in Washington, DC, on April 24, 2018. (Photo by Nicholas Kamm / AFP)        (Photo credit should read NICHOLAS KAMM/AFP/Getty Images)
PHOTO: NICHOLAS KAMM/AFP/Getty Images
US President Donald Trump and French President Emmanuel Macron hold a joint press conference at the White House in Washington, DC, on April 24, 2018. (Photo by Nicholas Kamm / AFP) (Photo credit should read NICHOLAS KAMM/AFP/Getty Images)
Now playing
00:55
Trump: If Iran threatens us, they will pay
President of France Emmanuel Macron addresses the United Nations General Assembly on September 25, 2018 in New York City.
PHOTO: John Moore/Getty Images
President of France Emmanuel Macron addresses the United Nations General Assembly on September 25, 2018 in New York City.
Now playing
00:43
Macron fires back at Trump in UNGA speech
PHOTO: POOL
Now playing
01:42
Trumps welcome Macrons to first state dinner
US President Donald Trump (L) and French President Emmanuel Macron (R) shake hands ahead of a working lunch, at the US ambassador's residence, on the sidelines of the NATO (North Atlantic Treaty Organization) summit, in Brussels, on May 25, 2017. / AFP PHOTO / Mandel NGAN        (Photo credit should read MANDEL NGAN/AFP/Getty Images)
PHOTO: MANDEL NGAN/AFP/Getty Images
US President Donald Trump (L) and French President Emmanuel Macron (R) shake hands ahead of a working lunch, at the US ambassador's residence, on the sidelines of the NATO (North Atlantic Treaty Organization) summit, in Brussels, on May 25, 2017. / AFP PHOTO / Mandel NGAN (Photo credit should read MANDEL NGAN/AFP/Getty Images)
Now playing
00:46
Macron: Trump handshake was moment of truth
French president-elect Emmanuel Macron greets supporters before delivering a speech in front of the Pyramid at the Louvre Museum in Paris on May 7, 2017, after the second round of the French presidential election.
 (Photo credit should read ERIC FEFERBERG/AFP/Getty Images)
PHOTO: ERIC FEFERBERG/AFP/Getty Images
French president-elect Emmanuel Macron greets supporters before delivering a speech in front of the Pyramid at the Louvre Museum in Paris on May 7, 2017, after the second round of the French presidential election. (Photo credit should read ERIC FEFERBERG/AFP/Getty Images)
Now playing
01:32
What to know about Emmanuel Macron
PHOTO: pool
Now playing
02:49
Macron warns US Congress: There's no Planet B
French President Emmanuel Macron speaks to a joint meeting of Congress on Capitol Hill in Washington, Wednesday, April 25, 2018. Standing behind him are Vice President Mike Pence and House Speaker Paul Ryan of Wis. (AP Photo/Pablo Martinez Monsivais)
PHOTO: Pablo Martinez Monsivais/AP
French President Emmanuel Macron speaks to a joint meeting of Congress on Capitol Hill in Washington, Wednesday, April 25, 2018. Standing behind him are Vice President Mike Pence and House Speaker Paul Ryan of Wis. (AP Photo/Pablo Martinez Monsivais)
Now playing
01:12
Macron: No democracy without truth
French President Emmanuel Macron arrives at the ancient Greek Theatre of Taormina during the Heads of State and of Government G7 summit, on May 26, 2017 in Sicily.
The leaders of Britain, Canada, France, Germany, Japan, the US and Italy will be joined by representatives of the European Union and the International Monetary Fund (IMF) as well as teams from Ethiopia, Kenya, Niger, Nigeria and Tunisia during the summit from May 26 to 27, 2017. / AFP PHOTO / Tiziana FABI        (Photo credit should read TIZIANA FABI/AFP/Getty Images)
PHOTO: TIZIANA FABI/AFP/AFP/Getty Images
French President Emmanuel Macron arrives at the ancient Greek Theatre of Taormina during the Heads of State and of Government G7 summit, on May 26, 2017 in Sicily. The leaders of Britain, Canada, France, Germany, Japan, the US and Italy will be joined by representatives of the European Union and the International Monetary Fund (IMF) as well as teams from Ethiopia, Kenya, Niger, Nigeria and Tunisia during the summit from May 26 to 27, 2017. / AFP PHOTO / Tiziana FABI (Photo credit should read TIZIANA FABI/AFP/Getty Images)
Now playing
01:01
Macron to US: Make our planet great again
President Donald Trump, French President Emmanuel Macron, first lady Melania Trump and Brigitte Macron hold hands on the White House balcony during a State Arrival Ceremony at the White House in Washington, Tuesday, April 24, 2018. (AP Photo/Pablo Martinez Monsivais)
PHOTO: Pablo Martinez/AP
President Donald Trump, French President Emmanuel Macron, first lady Melania Trump and Brigitte Macron hold hands on the White House balcony during a State Arrival Ceremony at the White House in Washington, Tuesday, April 24, 2018. (AP Photo/Pablo Martinez Monsivais)
Now playing
02:15
Cillizza's thoughts on picture of Trumps, Macrons
PHOTO: CNN
Now playing
01:08
Melania plans Trump's first state dinner
PARIS, FRANCE - JULY 13:  French President Emmanuel Macron welcomes US President Donald Trump prior to a meeting at the Elysee Presidential Palace on July 13, 2017 in Paris, France. As part of the commemoration of the 100th anniversary of the entry of the United States of America into World War I, US President, Donald Trump will attend tomorrow at the Bastille Day military parade.  (Photo by Thierry Chesnot/Getty Images)
PHOTO: Thierry Chesnot/Getty Images
PARIS, FRANCE - JULY 13: French President Emmanuel Macron welcomes US President Donald Trump prior to a meeting at the Elysee Presidential Palace on July 13, 2017 in Paris, France. As part of the commemoration of the 100th anniversary of the entry of the United States of America into World War I, US President, Donald Trump will attend tomorrow at the Bastille Day military parade. (Photo by Thierry Chesnot/Getty Images)
Now playing
01:51
How the Macron-Trump bromance evolved
Trump Macron long handshake dlewis_00000000.jpg
Trump Macron long handshake dlewis_00000000.jpg
Now playing
00:38
Trump's never-ending handshake with Macron
Macron and his wife Brigitte stand with Trump and First Lady Melania Trump during a welcoming ceremony at Les Invalides in Paris.
PHOTO: Yves Herman/pool/ap
Macron and his wife Brigitte stand with Trump and First Lady Melania Trump during a welcoming ceremony at Les Invalides in Paris.
Now playing
00:48
Trump comments on Macron's wife's appearance
US President Donald Trump (2nd R) shakes hands with French President Emmanuel Macron (2nd L) and his wife Brigitte Macron (L), next to US First Lady Melania Trump, during the annual Bastille Day military parade on the Champs-Elysees avenue in Paris on July 14, 2017.
The parade on Paris's Champs-Elysees will commemorate the centenary of the US entering WWI and will feature horses, helicopters, planes and troops. / AFP PHOTO / POOL AND AFP PHOTO / CHRISTOPHE ARCHAMBAULT        (Photo credit should read CHRISTOPHE ARCHAMBAULT/AFP/Getty Images)
PHOTO: CHRISTOPHE ARCHAMBAULT/AFP/AFP/Getty Images
US President Donald Trump (2nd R) shakes hands with French President Emmanuel Macron (2nd L) and his wife Brigitte Macron (L), next to US First Lady Melania Trump, during the annual Bastille Day military parade on the Champs-Elysees avenue in Paris on July 14, 2017. The parade on Paris's Champs-Elysees will commemorate the centenary of the US entering WWI and will feature horses, helicopters, planes and troops. / AFP PHOTO / POOL AND AFP PHOTO / CHRISTOPHE ARCHAMBAULT (Photo credit should read CHRISTOPHE ARCHAMBAULT/AFP/Getty Images)
Now playing
01:15
Trump and Macron at Bastille Day (2017)
Macron stands up against President Trump Bell pkg_00010411.jpg
Macron stands up against President Trump Bell pkg_00010411.jpg
Now playing
01:54
Macron takes a stand against Trump
trump marcron handshake akward alee_00002330.jpg
trump marcron handshake akward alee_00002330.jpg
Now playing
00:28
Watch Trump and Macron's extended handshake
(CNN) —  

Hours of intensive talks and elaborate displays of bonhomie between President Donald Trump and his French counterpart Emmanuel Macron on Tuesday failed to yield clarity on the fate of the Iran nuclear deal, which Trump has derided and Macron hopes to salvage.

More successful were Macron’s appeals to rethink an immediate exit of US troops from Syria, which Trump conceded could not happen until the US is able to “leave a strong and lasting footprint.”

It amounted to a split outcome for Macron, who arrived in Washington hoping to sway Trump away from isolationist decisions that loom in the coming months. Trump has insisted his pledges to rip up the Iran deal and bring American troops home from war amount to promises his voters expect him to fulfill.

Trump opened the day railing against the Iran accord, calling the Obama-era agreement “insane” and “ridiculous” for failing to contain Tehran.

Later, during a news conference, he sounded a more conciliatory note and maintained he could soon strike an agreement with his visitor, who laid out his own vision for pact.

“We can be flexible. You know, in life you have to be flexible, and as leaders of countries, you have to show flexibility,” Trump said.

But Trump declined to say whether he would sign on to a Europe-brokered supplemental agreement to the Iran deal. And he offered an ominous threat to Tehran should it resume its nuclear program.

“They will have bigger problems than they ever had before,” he said.

The lingering dispute over the Iran deal proved that neither dinners of Dover sole nor a glitzy military welcome could paper over the two leaders’ differences during an elaborate state visit, the first of Trump’s presidency.

Earlier in the day, the two men put forward an elaborate show of friendship on the South Lawn, reviewing cordons of troops in formation and recalling the long history between the US and France. They are due to sit for Trump’s inaugural state dinner on Tuesday evening, with rack of lamb and jambalaya on the menu.

PHOTO: AFP/Getty Images

Throughout the day, the two leaders sought to play up in their body language the image of a global “bromance.” But the persistent back-patting, handshaking and pecks on the cheek came ultimately to assume a competitive undertone, with the germ-averse Trump standing rigidly as Macron grasped his forearm and Trump happily flicking what he said was a flake of dandruff from Macron’s navy suit.

Macron acknowledged during his remarks Tuesday that he was visiting a strong-willed peer.

“It’s not a mystery, we did not have the same starting positions, and neither you nor I have a habit of changing our stances or going with the wind,” the French President said through a translator. “That being said, I can say that we’ve had a very frank discussions, just the two of us.”

Little clarity on Iran

Trump has threatened to pull out of the Iran deal and snap back US sanctions on Iran by May 12 unless major changes are made to the agreement brokered by the previous US administration, which capped Iran’s nuclear program in exchange for relief from economic sanctions.

Trump on Tuesday decried the deal as failing to address Iran’s ballistic missile program or its support of terror groups in the Middle East.

France, Germany and the United Kingdom – key signatories to the deal – are in the midst of negotiations with the US aimed at assuaging some of Trump’s concerns, but large gaps still remain.

Macron said on Tuesday he was open to a new agreement that would address Trump’s concerns while not tearing apart the existing deal. But Trump offered no indication of which direction he may go.

“Nobody knows what I’m going to do on the 12th,” Trump said, referring to the deadline. “This is a deal with decayed foundations. It’s a bad deal, it’s a bad structure, it’s falling down. It should have never, ever been made.”

Already, some US administration officials have been preparing options for withdrawal from the agreement, hoping to be ready should Trump abruptly make his announcement over Twitter. Macron’s visit was viewed as critical to swaying Trump toward a compromise, rather than the all-or-nothing approach he has signaled on the Iran deal.

Trump offered scant assurances to Macron that he was reconsidering his pledge to exit the Iran agreement. But he did signal a compromise may be near.

“We could have at least an agreement among ourselves fairly quickly,” he said during talks in the Cabinet Room. “I think we’re fairly close to understanding each other. And I think our meeting, our one-on-one went very, very well.”

And he signaled he was willing to reconsider his demand that US troops exit Syria soon, indicating he didn’t want other countries like Iran and Russia to gain a foothold.

“I do want to come home, but I want to come home also having accomplished what we have to accomplish,” he said.

Elaborate welcome

PHOTO: Jacquelyn Martin/AP

Trump is deploying the full trappings of formal state entertaining for the first time in the hopes an elaborate display of diplomacy can lead to a deeper bond with the young French leader. First lady Melania Trump, who emerged from the South Portico on Tuesday wearing a dramatic wide-brimmed white hat, has been overseeing preparations, including the three-course state dinner on Tuesday.

Standing before a military display on the South Lawn, Trump hailed the US-France alliance without mentioning the areas of difference. Macron, he said later, was doing a “great job” as President.

Macron, however, did not avoid the topic, saying the differences over climate change were surmountable.

“On this issue, we do not always agree as to the solutions, but in the end, such is the case in any family and in any friendship, and it is also where the fate of our children is at stake,” he said through a translator.

He also warned against the rise of “aggressive nationalisms that deny our history and divide the world,” a potent subject both in France, where anti-Semitism and nativist immigration stances have swelled, and the United States, where white nationalist rallies have drawn condemnation, though not from Trump.

“It is together that we will build a new strong multilateralism that defends pluralism and democracy in the face of ill winds,” Macron said.

Underlying competitiveness

The French leader – who has been dubbed a “Trump whisperer” by some – has forged one of the closest relationships Trump maintains with any world leader, some of whom he has openly feuded with or belittled.

But beneath the outward bonhomie is an underlying competitiveness, according to US and French officials familiar with the two men’s relationship. Both are alpha males highly attuned to their own reputations, and each entered office with grand promises of shattering their country’s political status quo. Officials in both countries have downplayed the notion of a “bromance,” insisting the two men are not close personal friends but rather closely aligned allies.

Ever since May, when the two men met for the first time inside the US ambassador’s residence in Brussels, fascination has swirled around their relationship. That first meeting was marked by strained grins and a lengthy, white-knuckled handshake that immediately went viral online.

Even before that session, which occurred on the sidelines of a NATO summit, Macron has carefully approached his interactions with an unpredictable American leader. He studied videos of Trump’s handshakes, which sometimes include a firm tug inward. He and his aides continue to closely monitor Trump’s Twitter feed for a daily reading of the US President’s mood and his shifting policy sentiments.

On Tuesday, the physical assertiveness continued. Macron seemed intent on kissing Trump on both cheeks, in the French style, upon every greeting. During their joint news conference, he reached over on occasion to grab Trump’s arm as he punctuated his point.

Trump, meanwhile, decided a photo opportunity on the Oval Office was the ideal moment to highlight Macron’s scalp care.

“I’ll get that little piece of dandruff off,” Trump said, brushing an invisible piece of dust from Macron’s shoulder.

“We have to make him perfect,” he said. “He is perfect.”

CNN’s Jeremy Diamond contributed to this report.