The intensifying violence in eastern Ukraine -- and fears of increased Russian involvement -- have gripped the attention of both the United States and Europe.
Officials are now intensely working on a response to calm tensions across the region, even as President Barack Obama spoke again with his Russian counterpart, Vladimir Putin, about the crisis.
European ministers arriving for talks in Luxembourg, wary of the violent turn of events in eastern Ukraine, had no problem placing blame Monday. British Foreign Secretary, William Hague, is pointing his finger squarely at Moscow.
"It has all the appearances of a further gross, deliberate and premeditated violation of the independence and sovereignty of Ukraine," he said.
Swedish Foreign Minister Carl Bildt is equally blunt.
“So far they've been escalating, and if they continue to escalate, I think we should escalate," he said.
Which is what they did, by agreeing to expand sanctions and visa bans against Russia.
Even as Europe moved for more actions, the U.S. military announced a Russian fighter jet, like these, made 12 low-altitude, close-range passes near the USS Donald Cook while patrolling international waters in the Black Sea Saturday.
Pentagon officials said the Russian jet was not armed with missiles but called the actions “provocative and unprofessional."
In Moscow, Russian Foreign Minister Sergei Lavrov hit back… accusing the West of encouraging Kyiv to crack down.
"This is an extremely dangerous development of the events, and those who encourage the current Kyiv authorities to act that way should bear full responsibility," he said.
Lavrov also questioned what U.S. spy chief John Brennan was doing in Kyiv this past weekend, a trip White House spokesman Jay Carney defended as “standard,” to promote security cooperation, warning Russia to step back:
“I can assure you that Russia’s provocations - further transgressions and provocation - will come with a cost,” he said.
Like the European Union, the U.S. says it is prepared to ramp up sanctions and, Monday, also announced a $1 billion loan guarantee for Ukraine.
Yet military aid - requested by Ukraine - has not been forthcoming - -- even as NATO worries about the massing of Russian troops along the border.
“It’s a question in which we hopefully do not revert to a Cold War in the sense really of the Western countries pairing up against Russia because Russian assistance in many worldwide situations is still very important,” said former U.S. Senator Richard Lugar.
For now, though, there are plenty of questions in the West about just how far Russia will go.
“These are not peaceful protesters, this is an armed force," said U.S. Ambassador to Ukraine Geoffrey Pyatt who spoke to VOA’s Russian Service. "And I think there is a real risk that their actions could precipitate greater violence and any bloodshed, of course, is something that the United States will oppose."
All the while, the tensions in Ukraine continue to rise.