Russia's high seas stunt off Ukraine is ramping up tensions at the G20

Once, G20 summits were dry affairs, where leaders tried to generate excitement around consensus initiatives couched in terms designed to offend no one and commit to nothing.

No longer. The G20 summit in Buenos Aires is looking more like a convention of cartoon villains, where even the 'family photo' is fraught with tension. (Who wants to stand next to Mohammed bin Salman? Anyone?)

Russian President Vladimir Putin arrives fresh from a major provocation in his ongoing conflict with Ukraine, just hours after a Crimean court ordered a dozen Ukrainian sailors — captured in an armed confrontation with the Russian navy in the Kerch Strait between the Black Sea and the Sea of Azov — held for prosecution.

The Russians also paraded some of the captured sailors on television — an apparent violation (in spirit, at least) of the Third Geneva Convention.

"Provocative actions of the Russian Federation in the Black Sea and the Sea of Azov have transgressed all boundaries and become aggressive," said a statement from the Ukrainian Embassy in Ottawa.

"I don't want anyone to think this is fun and games," said Ukrainian President Petro Poroshenko in a statement on national television. "Ukraine is under threat of full-scale war with Russia."

So much for deniability

One factor that makes such a war less likely is the certainty that Ukraine would be crushed, as both sides are well aware. The Russians also know that such a war would lead to a huge escalation with NATO and spark a new arms race — one which the sputtering Russian economy would be certain to lose.

Still, the latest moves represent a serious escalation for Russia, said Aurel Braun, professor of international relations at the University of Toronto and author of several books on Russia and NATO.

"Up 'til now, everything that Putin has done in Ukraine had an element of plausible deniability. We've seen this hybrid war, almost like shadow-boxing," said Braun.

Even the "little green men" who seized the Crimean peninsula in 2014 had removed their Russian Army insignia from their combat fatigues. Moscow insisted they were just local patriots who happened to be remarkably well-equipped and organized.

"This is different because it's the first overt hostile act by official Russian forces against Ukraine," said Braun. "It's a major challenge to NATO and to the European Union."

In Canada the Conservative opposition said the ship seizures demanded a response that Ottawa has so far been reluctant to embrace.

"Today we call on the Liberals to impose a wider range of sanctions against those responsible for the attack," said Conservative Party Leader Andrew Scheer. "We also urge the Trudeau government to provide lethal aid to Ukraine's military as we requested last spring."

The U.S. began shipping anti-tank missiles to Ukraine in April and has said it is ready to supply more arms. Canada, meanwhile, has delivered only non-lethal military supplies, such as medical kit, body armour and winter clothing. Canadian Forces are, however, heavily involved in training their Ukrainian counterparts at a base in Yavorivsky in Ukraine's west (far from the front lines in Eastern Ukraine).

Canada also is working to help Ukraine reform and modernize its outdated, Soviet-style defence department.

Trump isolated on Russia

President Donald Trump reacted to the Kerch Strait incident by threatening to cancel a planned bilateral meeting with Putin at the G20.

"Maybe I won't have the meeting," he told the Washington Post. "I don't like that aggression. I don't want that aggression at all."

Trump subsequently cancelled the bilateral with Putin in a tweet shortly after leaving Washington for the summit — not long after news broke that his former personal attorney, Michael Cohen, had pleaded guilty to lying to Congress about a Moscow real estate project that Trump and his company pursued as he was running for president.

"The U.S. response to Russia has been unusual because while the president's attitude has been friendly, even obsequious to Putin, the U.S. government's actions and policies have not," said Braun.

Braun said the question of whether the Russians have some hidden leverage over the president looms over the debate on how the U.S. should respond to Russia — but the U.S. government is more than just Donald Trump. The State Department has continued to sanction Russia and the Pentagon has worked to contain its moves against former Soviet republics such as Ukraine and the three Baltic nations.

Other NATO allies have also stepped up to provide assurances to the Baltic states. Canada has deployed 400 troops to Latvia. (Ukraine is not a NATO member, nor does it belong to the European Union.)

President Trump may be keen to avoid creating another rift over Russia with powerful senators from his own party, who in recent days have been highly critical of his handling of Saudi Arabia. Thirteen Republican senators broke ranks on Wednesday to support a motion to end American support for the Saudis' war on Yemen. The vote was both a defeat and a rebuke for an administration that lobbied heavily on Capitol Hill to avoid just such a result.

Distrust of the president's motives when it comes to Russia is one of the few issues that has united Democrats and Republicans in Congress. The U.S. Senate voted 98-0 in July 2017 to give itself the power to block President Trump from lifting sanctions against Russia. That vote followed Trump's controversial Helsinki summit, where he met privately with Putin — insisting that no U.S. official other than a translator be present.

'A hyena, not a tiger'

Tellingly, President Poroshenko appealed for help not to Trump, but to Germany's Angela Merkel, a Russian-speaker who has a personal rapport with Putin.

"Germany is one of our closest allies," Poroshenko told the Bild newspaper, "and we hope that states within NATO are now ready to relocate naval ships to the Sea of Azov to assist Ukraine and provide security."

That doesn't seem likely. While Merkel has said she wants the captured Ukrainian sailors released and the Russian blockade of Ukrainian ports on the Sea of Azov lifted, she also cautioned that "there is no military solution to these problems. We have to emphasize that."

"What remains to be seen," said Braun, "is whether NATO will now take the long-delayed step of deploying a large permanent force to Poland. That would send a very strong signal to Russia.

"Right now, Putin is probing for gaps and weaknesses. And in international affairs, any sign of weakness is an invitation.

"Putin's popularity is slipping at home, because with the price of oil and the uni-dimensionality of the Russian economy, he's not able to deliver economic growth, and so he tries to grow his popularity through these foreign adventures."

Braun said Putin is a calculating risk-taker, not a reckless adventurer. Just as he knows when to strike, he also has shown at times that he knows he can overplay his hand. He will wait and see how the leaders now assembling in Buenos Aires react to his latest move before he initiates another.

"Putin is a hyena," said Braun. "He's not a tiger."