PARIS/BERLIN/WASHINGTON - Is it better to engage with Russian President Vladimir Putin over his invasion of Ukraine or to isolate him? Should Kyiv make concessions to end the war, or would that embolden the Kremlin? Are ramped-up sanctions on Russia worth the collateral damage?

These are some of the questions testing the international alliance that swiftly rallied around Ukraine in the days after the Russian invasion but that, three months into the war, is straining, officials and diplomats told Reuters.

As Western governments grapple with spiralling inflation and energy costs, countries including Italy and Hungary have called for a quick ceasefire. That could pave the way for scaled-back sanctions and end the blockade of Ukrainian ports that has worsened a food security crisis for the world's poorest.

Yet Ukraine, Poland and the Baltics warn that Russia is not to be trusted and say a ceasefire would enable it to consolidate territorial wins, regroup and launch more attacks down the line.

The Russians have "spread the narrative that this would be an exhausting war, we should sit around the table and seek consensus," a senior Ukrainian official told Reuters.

US Secretary of Defence Lloyd Austin has said he wants Russia "weakened" and President Joe Biden called for Putin to be prosecuted for war crimes. British Prime Minister Boris Johnson says Kyiv must not be strong-armed into accepting a bad peace deal and that Ukraine "must-win".

Germany and France have remained more ambiguous, vowing to stop Putin from winning rather than to defeat him, while at the same time backing tough new sanctions.

"The question being asked is whether we return to the Cold War or not. That's the difference between Biden, Johnson and us," an ally of French President Emmanuel Macron told Reuters.

Russia launched what it calls a "special operation" in Ukraine in February, saying it was needed to rid the country of dangerous nationalists and degrade Ukraine's military capabilities - aims the West denounced as a baseless pretext.

Moscow has since argued that military support from Washington and allies is dragging out the war and deterring Ukraine from peace talks. In March, the Kremlin demanded Ukraine cease military action, change its constitution to enshrine neutrality, acknowledge Crimea as Russian, and recognise eastern separatist-held areas as independent states as a condition for peace.

The Ukrainian and French sources, and officials in other countries consulted by Reuters for this story, requested anonymity in order to speak freely about sensitive diplomatic and security policies.

Divisions could become more pronounced as sanctions and the war take a toll on the global economy, risking domestic backlashes and playing into Putin's hands.

"It was clear from the start it is going to get more and more difficult over time - the war fatigue is coming," Estonian Prime Minister Kaja Kallas said in an interview with CNN.

"There may be difference between those countries who have much better neighbours than we do, and those who have a different history like us, the Baltic countries, and Poland."

Dealing with Mr Putin

Macron has warned any peace should not "humiliate" Russia as it did for Germany in 1918.

He, like German Chancellor Olaf Scholz, has kept channels of communication with the Kremlin open, triggering consternation in more hawkish countries. Poland's president compared the calls to speaking with Adolf Hitler during World War Two. 

"We'll have to deal with Mister Putin at some point unless there's a palace coup. And even more so because this war needs to be as short as possible," the Macron ally said.

Scholz said his and Macron's calls with Putin were used to convey firm and clear messages and has stressed sanctions on Russia would not end unless Putin withdrew troops and agreed to a peace deal acceptable to Kyiv.

However, one of Scholz's team told Reuters that Macron's wording had been "unfortunate." Some French diplomats have also privately expressed reservations about Macron's stance, saying it risked alienating Ukraine and eastern European allies.

While grateful for the West's support, Ukraine has bristled at suggestions that it should concede territory as part of a ceasefire deal and sometimes questioned whether its allies were properly united against Russia.

Macron's warning not to humiliate Russia prompted Ukraine's Foreign Minister Dmytro Kuleba to warn that France was only humiliating itself, and Kyiv's relations with Scholz have been frosty.

"We don't have a Churchill across the European Union. We do not have any illusions on that," the senior Ukrainian official said, referring to Britain's wartime Prime Minister Winston Churchill.

ALSO READ: Putin compares Ukraine actions with Peter the Great's conquests

A French presidency official said, "there is no spirit of concession with regard to Putin or Russia in what the president says." France wanted a Ukrainian victory and Ukrainian territories restored, the official said, and dialogue with Putin was "not to compromise but to say things as we see them".

A US administration official said Washington was more vocal in its scepticism about Russia acting in good faith, but denied there was a "strategic difference" between allies.

A State Department spokesperson told Reuters that the US working along with allies had "delivered," for Ukraine - with sanctions, weapons transfers and other measures - despite naysayers since before the invasion casting doubt on the unity of the alliance. The goal, the spokesperson said, was to put Ukraine in a strong position to negotiate.

Weaken Russia?

Referring to Austin's comments, the first official said Washington had no intention of changing Russia's leadership but wanted to see the country weakened to the point that it couldn't carry out such an attack on Ukraine again.

"Everyone focused on the first part of what Austin said not on the second part. We want to see Russia weakened to the extent that it can't do something like this again," the official said.

One German government source said Austin's aim to weaken Russia was problematic. It was unfortunate that German Foreign Minister Annalena Baerbock, from Scholz's coalition partner the Greens, had endorsed that aim, the source said, because it complicated the question of when sanctions could ever be lifted, irrespective of whether Ukraine agreed to a peace deal or not.

German government sources also said they were worried that some in the West could be egging on Ukraine to unrealistic military goals, including the recapture of the Crimea peninsula annexed by Russia in 2014, that could prolong the conflict.

Baerbock has publicly said sanctions would have to remain in place until Russian troops withdrew from Crimea.

Ukraine's ambassador to Germany meanwhile has repeatedly criticised Germany for dragging its feet on sending heavy weapons to Ukraine, though Berlin has robustly defended its record of support.

President Volodymyr Zelenskiy's senior adviser Mykhailo Podolyak signalled Ukraine's frustrations:

"Russia must not win, but we won't give heavy weapons - it may offend Russia. Putin must lose but let's not impose new sanctions. Millions will starve, but we're not ready for military convoys with grain," he tweeted on May 31.

"Rising prices are not the worst that awaits a democratic world with such a policy," he said.

Source: Reuters