After weeks of watching supposed allies trade allegations of betrayal and of insulting each others' troops, delegates to the NATO Summit in London this week might be wondering who their friends are these days.

But bitter as the recriminations have been, there's an even bigger cloud hanging over the summit: doubts about the fundamental principle of trust upon which NATO was built 70 years ago.

For decades, the 29 countries making up NATO have been reassured by the treaty's ironclad guarantee of mutual defence in Article Five of its founding charter: "an armed attack against one or more of them in Europe or North America shall be considered an attack against them all."

But in the era of U.S. President Donald Trump, governments now have doubts about the United States' commitment to Article Five. The mutual defence clause has only ever been invoked once — by Canada on behalf of the U.S. in the immediate aftermath of the September 11, 2001 terrorist attacks.

The 158 Canadian soldiers and seven Canadian civilians who lost their lives in Afghanistan died upholding Article Five. The NATO alliance only works when members trust that others will answer when the call comes.

Military analyst Dave Perry of the Canadian Global Affairs Institute said NATO allies still trust the U.S. military, American institutions and the individual Americans they work with in the alliance.

"The concern is really about a president who keeps demonstrating, over and over again, that he has a very different view of how America should be relating to its allies," he said.

"The American president has left the impression at times that he's got better relations with the Russian president than he does with some of the heads of NATO allies in Europe or even Canada."

A legacy of disloyalty

Ivo Daalder, president of the Chicago Council on Global Affairs, was the U.S. permanent representative on the NATO Council for four years under President Barack Obama.

He said President Trump has undermined the alliance by sowing doubts about America's intentions.

"He has said many times that NATO is obsolete. He refused for the first six months of his presidency to reaffirm Article Five, and has called into question whether the United States should continue to be a member of NATO if the allies are not willing to spend more on defence," he said.

"It's those kinds of questions that lead allies to say, 'If the chips are down, will the U.S. be there?' And there's less confidence about that today than there used to be."

Kurdish forces withdraw from an area near Turkish border with Syria, overseen by the Russian forces, near the town of Amuda, Sunday, Oct. 27, 2019. (Baderkhan Ahmad/The Associated Press)

Daalder said Trump has undermined that trust through both his words and his actions.

"President Trump has taken a number of steps, including abandoning his Kurdish allies in Syria, that would call into question his commitment to alliance relationships," he said.

Perry agrees that the betrayal of the Kurds sent a shiver through the Western alliance.

"It's not just that the United States bailed out on the Kurds, because I think we've seen a version of that movie before. It's the no-notice way of doing it, and the fact that the president would make these kinds of decisions not only capriciously, but also appearing to have totally ignored any advice that he did bother to solicit," he said.

"The president's whims are increasingly being translated into tangible outcomes. People have been speculating for several years that the president will send some tweets, but then the 'grown-ups' will prevail. I think the Syria example shows that the 'grown-ups-prevailing' narrative may be coming to an end."

Fighting with France

While some European leaders expressed their doubts in private, France's President Emmanuel Macron made his public in a recent interview with The Economist. In it, Macron said NATO was suffering "brain death" and openly questioned Article Five.

Daalder said the French leader's concerns about the United States' reliability as an ally may be affected by his own ambitions to lead Europe.

"My reading of President Macron's latest statements are back in this Gaullist perspective that France needs to lead Europe," he said. "I'm gratified that the reaction to that from allies within Europe has been to say, 'Don't call into question the fundamental nature of the alliance with the United States, and indeed with Canada,' while at the same time trying to say how can we do more ourselves within a European context."

Turkey's President Recep Tayyip Erdogan, right, shakes hands with French President Emmanuel Macron during the G-20 summit in Osaka, Japan June 28, 2019. (The Associated Press/Presidential Press Service)

On Thursday, Macron defended his harsh language and expanded on it.

"The questions I have asked are open questions that we haven't solved yet — peace in Europe, the Intermediate-Range Nuclear Forces Treaty, the relationship with Russia, the issue of Turkey," he said. "Who is the enemy?

"So I say, as long as these questions are not resolved, let's not negotiate about cost-sharing and burden-sharing, or this or that. Maybe we needed a wake-up call, as they say in English. I'm glad it was delivered, and I'm glad everyone now thinks we should rather think about our strategic aims."

But the U.S. does want to talk about cost-sharing; in fact, the Trump administration announced unilaterally this week that it intends to cut its contribution to NATO's total budget from 22 per cent to 16 per cent. Other members, including Canada, will have to pick up the slack.

Feuding with Germany

It's a feature of NATO that the closer its members are to Russia, the more likely they are to meet the desired threshold of spending at least 2 per cent of GDP on defence.

Bulgarian Prime Minister Boyko Borissov, while visiting President Trump in the Oval Office on Monday, made a point of noting that his country spends 3.1 per cent of its GDP on defence.

"You should tell that to Germany," Trump huffed.

Trump has singled Germany out for failing to spend enough on the alliance, although his administration also is pressuring Canada.

German Chancellor Angela Merkel, left, and U.S. President Donald Trump pose for a photograph prior to a bilateral meeting on the sideline of a summit of heads of state and government at NATO headquarters in Brussels July 11, 2018. (Markus Schreiber/Associated Press)

In the run-up to the NATO summit, the U.S. and Germany have been feuding over another topic familiar to Canadians: Huawei.

Like their Canadian counterparts, Germany's leaders are wrestling with whether to permit the Chinese company to bid on contracts to build its 5G networks. Berlin has been subjected to a pressure campaign by Washington to ban Huawei as a potential security risk.

On Sunday, German minister Peter Altmaier recalled during a TV debate that it was the Americans — not the Chinese — who were caught spying on Germans through the PRISM program exposed by Edward Snowden in 2013.

Pointing out that Germany had not boycotted the U.S. companies that facilitated that spying, Altmaier reminded Germans that "the U.S. also demands from its companies that they pass on information."

Back in 2013, when German Chancellor Angela Merkel personally reproached President Obama about the bugging of her phone, he apologized and promised to make changes to the program.

U.S. Ambassador Richard Grenell said Altmaier's remarks were "an insult to the thousands of American troops who help ensure Germany's security and the millions of Americans committed to a strong Western alliance."

Turkey: With friends like these….

Meanwhile, Turkey continues to behave more like an adversary than a member of the NATO alliance, doubling down on its arms purchases from NATO's main strategic rival Russia — and threatening other members with sending jihadists captured in Syria back to their European countries of origin if their governments don't stop complaining about Turkey's actions in Syria.

Turkey has depended on President Trump to shield it from U.S. retaliation over its attack on Kurdish enclaves in Northern Syria, which infuriated both Republicans and Democrats. At the same time, it has counted on Trump to block enforcement of a U.S. law that requires Washington to impose sanctions on Turkey for installing Russian-made S-400 air defence systems.

On Thursday, Turkish Foreign Minister Mevlut Cavusoglu castigated Macron for hosting a delegate from the Kurdish YPG last month.

"He is already the sponsor of the terrorist organization and constantly hosts them at the Elysée. If he says his ally is the terrorist organization ... there is really nothing more to say," said Cavusoglu.

"Right now, there is a void in Europe. [Macron is] trying to be its leader."

'You are brain dead'

Macron shot right back, arguing Turkey's attack on the Kurds was at cross-purposes with NATO's mission to defeat the Islamic State.

"One cannot say on one hand that we're allies, and consequently demand our solidarity, and on the other hand put one's allies in the face of a military offensive delivered as a fait accompli that endangers the action of the coalition against the Islamic State," he said.

And on Friday, Turkish President Recep Tayyip Erdogan upped the stakes again, accusing "some countries that are accustomed to not taking risks and always winning" of being unable to "tolerate Turkey's efforts to protect its own rights, laws, borders and sovereignty. Most particularly, the latest comments of French president are the examples of this sick and shallow understanding.

"[Macron] says NATO is experiencing a brain death. I'm addressing Mr. Macron from Turkey and I will say it at NATO: You should check whether you are brain dead first."

Pardoning war criminals

As if the rancour wasn't enough, Perry said that President Trump is sowing new doubts by pardoning convicted war criminals.

"For all its warts, the U.S. has long been an upholder of the laws of armed conflict. For him to be intervening in that process of maintaining order and discipline is extraordinarily troubling," he said, citing Trump's recent decision to intervene in a disciplinary case against a Navy SEAL accused of war crimes in Iraq.

"From allies' perspective, it's another piece falling on top of the Syria withdrawal. It's increasingly uncertain what the United States stands for. You're not as sure now what it means to contribute to an American military operation as you would have been even a year ago."