Washington (CNN) -- It's trust in English, confiance in French, and a word used a lot Tuesday by President Barack Obama and visiting French President Francois Hollande to describe what has changed once thorny relations between the NATO allies.
At a news conference on the second day of Holland's state visit, the two leaders talked up continuing a new cooperation between their governments that butted heads a decade ago over the Iraq War.
Obama will host Hollande at a state dinner on Tuesday night -- the first of his second term -- in another sign of what both depicted as a diplomatic bromance in the face of international challenges that include the Syrian civil war, Iran's nuclear ambitions and economic malaise in Europe.
"We're standing shoulder to shoulder on key challenges," Obama said at one point, while Hollande declared that "we trust each other in an unprecedented manner."
Obama to France in June
To underscore the improving relations, Obama said he would travel to France in June at Hollande's invitation to mark the 70th anniversary of the Normandy invasion during World War II.
For his part, Hollande said that "mutual trust has been restored" between his government and the Obama administration in the aftermath of classified leaks by Edward Snowden that disclosed widespread U.S. surveillance operations in foreign countries.
A socialist elected in 2012, Hollande arrived alone for the trip after revelations in France of an affair with an actress and the subsequent end of his longtime relationship with Valerie Trierweiler, who was considered the equivalent of the French first lady even though they weren't married.
During Tuesday's news conference that stretched to an hour, no one asked about Hollande's personal life.
Even for issues on which they may not see completely eye-to-eye, Obama and Hollande emphasized a cooperative spirit in seeking an end to the Syrian war and a deal with Iran to prevent it from developing nuclear weapons.
Asked about the nuclear talks with Iran involving their countries along with Russia, Britain, China and Germany, the two leaders avoided directly answering if France had concerns that the United States might push for a less-than-ideal final agreement in order to declare success.
It's up to the Iranians to guarantee their intentions are for peaceful use of nuclear power, Obama said, adding that "if they meet what technically gives us those assurances, then there is a deal to be made. If they don't, there isn't."
For his part, Hollande said a six-month agreement reached with Iran to freeze its enrichment in return for easing some sanctions while talks continue "doesn't mean that there is no longer an Iranian problem."
"There is an Iranian problem, for we need to make sure that Iran renounce the nuclear weapon in a definite and comprehensive manner," he said.
Obama has stressed the United States would enforce remaining U.S. and U.N. sanctions on Iran, pending a permanent accord on the nuclear issues.
When a reporter asked about a French business delegation visiting Iran, Obama warned any companies violating sanctions would "do so at their own peril now, because we will come down on them like a ton of bricks."
He added that the United States expects allies such France to fully observe existing sanctions against Iran.
Hollande, meanwhile, said it was critical that Iran renounces nuclear weapons in a "comprehensive manner" in talks going forward, but noted that he lacked authority to tell French businesses who they can talk with as long as no sanctions violations occur.
The next round of Iran talks begin on February 18 in Vienna. Iranian and International Atomic Energy Agency officials jointly said Sunday that Iran has agreed to take additional steps by May to ease international concern over Tehran's nuclear program.
On another Middle East issue dominating global concern, Obama said there was "a horrendous situation on the ground in Syria" and he called the ongoing civil war and humanitarian crisis "one of our highest national security priorities" because of extremists gaining greater influence in the "crumbling" nation.
Obama also said his administration was putting pressure on Russia -- a major ally of Syrian President Bashar al-Assad -- to help the international community gain access to provide humanitarian aid.
The message to Moscow was that expressions of concern about the welfare of Syrians were not enough "if there are starving people," Obama said.
Hollande noted the threats of military action by their countries that he credited with forcing the Syrians to negotiate the handover of its known chemical weapons stockpiles.
However, he said Syria's compliance with an agreement worked out by Russia had brought "only partial destruction" of Syrian chemical weapons so far that he said "doesn't go nearly far enough."
CNN's Moni Basu, Kevin Liptak and Matt Smith contributed to this report.