The poor prime minister of Montenegro, a country with less people than El Paso, Texas, learned this the hard way when Trump gave him a big shove on Thursday to get to the front of a pack of world leaders.
Secretary-General Jens Stoltenberg said Thursday that joining the USA -led anti-Islamic State coalition "will send a strong political message of NATO's commitment to the fight against terrorism and also improve our coordination within the coalition".
In the Middle East, President Donald Trump was feted with pageantry, the leaders of Saudi Arabia and Israel seemingly in competition to outdo the other with the warmth of their welcomes and the depth of their pledges of cooperation.
Even if a decision is not forthcoming, European leaders have signaled that they will push Trump hard on the Paris emissions deal, which has comprehensive support across the continent. He added, "Many of these nations owe massive amounts of money from past years".
In one nod to Trump, NATO leaders are due to agree later on Thursday for the Western military bloc to join the US-led, 68-nation coalition against Islamic State in Syria and Iraq.
Trudeau is to meet with newly elected French President Emmanuel Macron Friday morning before the start of the G7. Rand Paul said he applauded Trump's stance.
Only five members now meet the target: Britain, Estonia, debt-laden Greece, Poland and the United States, which spends more on defense than all the other allies combined.
Mr Trump's comments may disappoint some officials in Europe who had hoped that the USA president would offer a public endorsement of Nato's mutual-defense doctrine at the ceremony that honored Article 5, as the provision is known.
Montenegro will formally become NATO's 29th member on June 5, the alliance announced on Thursday, amid bitter Russian opposition to the move.
"Terrorism must be stopped or. the horror you saw in Manchester and so many other places will continue forever", Trump said, referring to Monday's suicide bombing in the northern English city that killed 22 people, including children.
It's a reminder of NATO's commitment to its collective defence clause - so-called Article 5 - which commits allies to defend any of the 28 members that come under attack.
NATO's current spending target of two percent of GDP on defence is not due to be met until 2024.
Stoltenberg is not too concerned about the fact that Trump did not openly say he is bound to Article 5. When Macron came around to Trump this time, having warmly greeted Merkel, the American president grabbed his hand and appeared to attempt the novel joint-dislocation handshake.
"It is too early to say whether that can be an issue".
"We agreed on many areas, first and foremost on counterterrorism", Tusk said after the one-hour meeting.
Trump then stood near Markovic and spoke to Lithuanian President Dalia Grybauskaite. The U.K. authorities said they had stopped sharing information about the Manchester bombing with the USA after information and a photo of the bombing that British intelligence shared with their US counterparts were leaked to the media.
"One way North Atlantic Treaty Organisation countries, including the United Kingdom, can play a positive role in the Middle East is to stop arming and supporting human rights-abusing regimes and pouring weapons into the region", Mr Smith said.