Senior diplomats from the major players trying to find an end to the crisis in Ukraine are gathering in Paris.
Envoys from Russia, Ukraine, the US, UK and France are not necessarily all at the same table, but French foreign minister Laurent Fabius said everyone has been working non-stop for a diplomatic solution.
"We're working on it," Mr Fabius told the BFM television network just ahead of a meeting with his Ukrainian counterpart. "There is no military solution."
Russia took over the strategic Crimean peninsula on Saturday, placing troops around its ferry port, military bases and border posts.
Today's gathering, originally scheduled to deal with the Syrian refugee crisis, came after Russian president Vladimir Putin appeared to step back from the brink of war.
It comes the day after US secretary of state John Kerry met the new Ukraine administration's acting president, prime minister, foreign minister and top parliamentary officials.
Mr Kerry promised American aid was on the way as he visited sites in Kiev where more than 80 anti-government protesters were killed last month.
Speaking to reporters afterwards, Mr Kerry said the US is looking for ways to de-escalate the mounting tensions.
"It is clear that Russia has been working hard to create a pretext for being able to invade further," he said.
"It is not appropriate to invade a country, and at the end of a barrel of a gun dictate what you are trying to achieve. That is not 21st-century, G8, major nation behaviour."
Mr Kerry made a pointed distinction between the Ukrainian government and that of Russian president Vladimir Putin.
"The contrast really could not be clearer: determined Ukrainians demonstrating strength through unity, and the Russian government out of excuses, hiding its hand behind falsehoods, intimidation and provocations.
"In the hearts of Ukrainians and the eyes of the world, there is nothing strong about what Russia is doing."
He said the penalties against Russia are "not something we are seeking to do, it is something Russia is pushing us to do".
President Barack Obama said his administration's push to punish Mr Putin put the US on "the side of history that, I think, more and more people around the world deeply believe in, the principle that a sovereign people, an independent people, are able to make their own decisions about their own lives".
"Mr Putin can throw a lot of words out there, but the facts on the ground indicate that right now he is not abiding by that principle."
The Ukraine government is grappling with a Russian military takeover of Crimea, a strategic, mostly pro-Russian region in the country's south east, and Mr Kerry's visit came as Mr Putin said he would not be deterred by economic sanctions imposed punitively by the West.
Ukraine foreign minister Andrii Deshchytsia told reporters that Ukraine was in a much stronger position than it was a week ago, having rallied the support of the US and the West.
He said it was unlikely Kiev would ever go to war to prevent Russia from annexing Crimea but said doing so would not be necessary, describing the economic penalties and diplomatic isolation more painful to Russians than bullets would be.
US officials travelling with Mr Kerry said the Obama administration is considering economic sanctions against Russia as soon as this week.
Members of Congress say they are preparing legislation that would impose sanctions as well.
Officials said the sanctions could be implemented in tiers, with an initial round of penalties targeted at individuals the US says were involved in the ousted Ukrainian government's corrupt activities.
Mr Putin is almost certain to be excluded from those penalties, the officials said, adding that it is rare for the US to directly target a head of state.