WASHINGTON, DC - JULY 17:  U.S. President Donald Trump talks about his meeting with Russian President Vladimir Putin, during a meeting with House Republicans in the Cabinet Room of the White House on July 17, 2018 in Washington, DC. Following a diplomatic summit in Helsinki, Trump faced harsh criticism after a press conference with Putin where he would not say whether he believed Russia meddled with the 2016 presidential election. (Photo by Mark Wilson/Getty Images)
Mark Wilson/Getty Images North America/Getty Images
WASHINGTON, DC - JULY 17: U.S. President Donald Trump talks about his meeting with Russian President Vladimir Putin, during a meeting with House Republicans in the Cabinet Room of the White House on July 17, 2018 in Washington, DC. Following a diplomatic summit in Helsinki, Trump faced harsh criticism after a press conference with Putin where he would not say whether he believed Russia meddled with the 2016 presidential election. (Photo by Mark Wilson/Getty Images)
Now playing
02:18
Trump questions commitment to defend NATO allies
Shutterstock
Now playing
02:37
Montenegro residents laugh off Trump's remarks
National Security Advisor John Bolton listens as US President Donald Trump addresses the nation on the situation in Syria April 13, 2018 at the White House in Washington, DC. Trump said strikes on Syria are under way.  / AFP PHOTO / Mandel NGAN        (Photo credit should read MANDEL NGAN/AFP/Getty Images)
MANDEL NGAN/AFP/Getty Images
National Security Advisor John Bolton listens as US President Donald Trump addresses the nation on the situation in Syria April 13, 2018 at the White House in Washington, DC. Trump said strikes on Syria are under way. / AFP PHOTO / Mandel NGAN (Photo credit should read MANDEL NGAN/AFP/Getty Images)
Now playing
00:50
Bolton criticized Trump's NATO stance in 2016
Trump NATO
POOL
Trump NATO
Now playing
01:09
Trump: Alliance to NATO remains 'very strong'
US President Donald Trump gestures as he addresses a press conference on the second day of the North Atlantic Treaty Organization (NATO) summit in Brussels on July 12, 2018. (Photo by Brendan SMIALOWSKI / AFP)        (Photo credit should read BRENDAN SMIALOWSKI/AFP/Getty Images)
BRENDAN SMIALOWSKI/AFP/Getty Images
US President Donald Trump gestures as he addresses a press conference on the second day of the North Atlantic Treaty Organization (NATO) summit in Brussels on July 12, 2018. (Photo by Brendan SMIALOWSKI / AFP) (Photo credit should read BRENDAN SMIALOWSKI/AFP/Getty Images)
Now playing
00:52
Trump explains what he thinks of Putin
Trump NATO 2
POOL
Trump NATO 2
Now playing
00:25
Trump to reporter: I'm a very stable genius
U.S. President Donald Trump speaks during a press conference after a summit of heads of state and government at NATO headquarters in Brussels, Belgium, Thursday, July 12, 2018. NATO leaders gather in Brussels for a two-day summit. (AP Photo/Geert Vanden Wijngaert)
Geert Vanden Wijngaert/AP
U.S. President Donald Trump speaks during a press conference after a summit of heads of state and government at NATO headquarters in Brussels, Belgium, Thursday, July 12, 2018. NATO leaders gather in Brussels for a two-day summit. (AP Photo/Geert Vanden Wijngaert)
Now playing
03:41
Fact-checking Trump's NATO claims
NATO Secretary General Jens Stoltenberg (L), US President Donald Trump (R), NATO Assistant Secretary General for Political Affairs and Security Policy Alejandro Alvargonzalez (2L), NATO Spokesperson Oana Lungescu (3L) and White House Chief of Staff John Kelly (3R) and US Ambassador to NATO Kay Bailey Hutchison (2R) speak at a breakfast meeting at the US chief of mission's residence in Brussels on July 11, 2018, ahead of a NATO (North Atlantic Treaty Organization) summit. Brendan Smialowski/AFP/Getty Images
Brendan Smialowski/AFP/Getty Images
NATO Secretary General Jens Stoltenberg (L), US President Donald Trump (R), NATO Assistant Secretary General for Political Affairs and Security Policy Alejandro Alvargonzalez (2L), NATO Spokesperson Oana Lungescu (3L) and White House Chief of Staff John Kelly (3R) and US Ambassador to NATO Kay Bailey Hutchison (2R) speak at a breakfast meeting at the US chief of mission's residence in Brussels on July 11, 2018, ahead of a NATO (North Atlantic Treaty Organization) summit. Brendan Smialowski/AFP/Getty Images
Now playing
01:49
Trump's NATO comment made his own staff squirm
U.S. President Donald Trump attends a meeting of the North Atlantic Council during a summit of heads of state and government at NATO headquarters in Brussels on Wednesday, July 11, 2018. NATO leaders gather in Brussels for a two-day summit to discuss Russia, Iraq and their mission in Afghanistan. (AP Photo/Geert Vanden Wijngaert)
Geert Vanden Wijngaert/AP
U.S. President Donald Trump attends a meeting of the North Atlantic Council during a summit of heads of state and government at NATO headquarters in Brussels on Wednesday, July 11, 2018. NATO leaders gather in Brussels for a two-day summit to discuss Russia, Iraq and their mission in Afghanistan. (AP Photo/Geert Vanden Wijngaert)
Now playing
02:05
Trump unleashes on allies at NATO summit
CNN
Now playing
01:00
NATO secretary general: We have to invest more
POOL
Now playing
01:30
Trump: Germany held captive by Russia
ZAGAN, POLAND - JUNE 18:  A soldier of the Polish Army mans a tank as a NATO flag flies behind during the NATO Noble Jump military exercises of the VJTF forces on June 18, 2015 in Zagan, Poland. The VJTF, the Very High Readiness Joint Task Force, is NATO's response to Russia's annexation of Crimea and the conflict in eastern Ukraine. Troops from Germany, Norway, Belgium, Poland, Czech Republic, Lithuania and Holland were among those taking part today.  (Photo by Sean Gallup/Getty Images)
Sean Gallup/Getty Images Europe/Getty Images
ZAGAN, POLAND - JUNE 18: A soldier of the Polish Army mans a tank as a NATO flag flies behind during the NATO Noble Jump military exercises of the VJTF forces on June 18, 2015 in Zagan, Poland. The VJTF, the Very High Readiness Joint Task Force, is NATO's response to Russia's annexation of Crimea and the conflict in eastern Ukraine. Troops from Germany, Norway, Belgium, Poland, Czech Republic, Lithuania and Holland were among those taking part today. (Photo by Sean Gallup/Getty Images)
Now playing
01:23
What's the point of NATO?
CNN
Now playing
02:20
NATO ambassador: Discord music to Putin's ears
US President Donald Trump speaks during a meeting with NATO Secretary General Jens Stoltenberg in the Oval Office of the White House in Washington, DC, May 17, 2018. (Photo by SAUL LOEB / AFP)        (Photo credit should read SAUL LOEB/AFP/Getty Images)
SAUL LOEB/AFP/Getty Images
US President Donald Trump speaks during a meeting with NATO Secretary General Jens Stoltenberg in the Oval Office of the White House in Washington, DC, May 17, 2018. (Photo by SAUL LOEB / AFP) (Photo credit should read SAUL LOEB/AFP/Getty Images)
Now playing
02:41
Trump blasts NATO allies ahead of summit
NATO flag flying at NATO Headquarters Brussels.
From NATO/From NATO/From NATO
NATO flag flying at NATO Headquarters Brussels.
Now playing
02:23
What Trump says about NATO and what it actually does
(CNN) —  

The country of Montenegro was thrust into the limelight after President Donald Trump was asked whether the US would come to the military aid of the most recent member of NATO.

Trump, in an interview on Fox News, appeared to cast doubt on his willingness to defend the country, calling the people of Montenegro “strong” and “aggressive,” suggesting that its aggressiveness could draw the US into World War III due to the NATO’s mutual security clause enshrined in Article 5 of the NATO treaty. It deems an attack on one member of NATO an attack on all countries in the alliance.

Article 5 – which is defensive – aims to deter potential adversaries from attacking NATO members. During the Cold War, the main concern was the Soviet Union, but in recent years, Russia’s aggressive actions in Eastern Europe have been the focus of attention. Ukraine and Georgia, the two countries Russia has invaded in the past decade, are not NATO members.

“Our collective defense clause, Article 5, is unconditional and iron-clad. It means that an attack on one is an attack on all. President Trump has made clear that the US is fully committed to NATO and our Alliance is stronger than ever,” a NATO official told CNN.

The southeastern European country is the newest member of NATO, having joined the alliance in 2017, the Alliance’s first expansion since 2009 when Albania and Croatia joined.

As NATO is a treaty alliance, the addition of new members requires approval of the US Senate and Montenegro’s membership was supported by a large bipartisan majority, which voted 97 to 2 to allow the country to join. Trump also signed off on the country’s joining soon thereafter.

Montenegro’s strategic location on the Adriatic coast ensured that the entire coastline is now made-up exclusively of NATO members.

Russia opposed Montenegro joining NATO

Russia was vehemently opposed to Montenegro’s joining the alliance, issuing statements of opposition. Moscow maintains close relationships with Montenegro’s neighbor Serbia and Moscow has sought to maintain its influence in the region.

Serbia and Montenegro were once part of the same country, Yugoslavia, and later in a union with Serbia until Montenegro’s vote for independence in 2006.

Additionally the government of Montenegro accuses Moscow of orchestrating an attempt to topple the government and assassinate the Montenegrin Prime Minister as part of an effort to stop its NATO bid.

Russia has recently been accused of similarly attempting to sabotage another Balkan country’s NATO bid, Macedonia, with Greece expelling Russian diplomats over the issue.

Senate Armed Services Chairman John McCain said Trump “is playing right into Putin’s hands” with his comments on Montenegro.

McCain tweeted, “The people of #Montenegro boldly withstood pressure from #Putin’s Russia to embrace democracy. The Senate voted 97-2 supporting its accession to #NATO. By attacking Montenegro & questioning our obligations under NATO, the President is playing right into Putin’s hands.”

He added, “#Putin will do anything to shatter the transatlantic alliance. In 2016, he nearly succeeded in overthrowing #Montenegro’s democratically elected government & murdering its prime minister in order to prevent it from joining #NATO”

Despite having a small military, only about 1,500 troops, Montenegro has been an active participant in NATO missions.

It currently has 20 troops serving in Afghanistan as part of the NATO-led training mission there.

Article 5 has only been invoked once to aid the US

Article 5 has only been invoked once, in support of the United States after the 9/11 attacks. This led to NATO’s largest-ever military operation, in Afghanistan, where hundreds of thousands of Europeans and Canadians stood shoulder-to-shoulder with US troops and more than 1,000 paid the ultimate price,” the NATO official told CNN.

Montenegro spends approximately 1.58% of its GDP on defense, making it one of the NATO members that does not currently hit the NATO recommended target of 2% of GDP. However, the country plans to reach that target by 2024 in accordance with the pledges made be all NATO allies at the Wales Summit. Trump has repeatedly slammed NATO members for not spending adequately on defense.

It’s not the first time Trump’s interaction with Montenegro has drawn scrutiny, Trump was famously seen on camera apparently pushing the country’s Prime Minister, Duško Marković, out of the way immediately prior to a photo op involving all the NATO leaders at the 2017 summit.

The Prime Minister appeared to downplay Trump’s comments Wednesday while responding to questions from parliamentarians.

“(Trump) said that the Montenegrin people (are) brave and that he does not want US citizens to fight for others and for other NATO member states. He did not say this only on that occasion but he also said the same at the NATO Summit,” Marković said.

Trump’s comments on Fox News stand in contrast to a statement issued by the White House in April 2017 following Trump’s signing of the instrument of ratification that allowed for Montenegro’s joining of NATO

“President Trump congratulates the Montenegrin people for their resilience and their demonstrated commitment to NATO’s democratic values,” the White House press secretary said.

CNN’s Jeremy Herb and Steve Brusk contributed reporting