President Barack Obama and British Prime Minister David Cameron laid down a new deadline for Russia on Thursday, giving Moscow a month to meet their conditions in Ukraine or face further sanctions.
Russian President Vladimir Putin, the focus of intensifying diplomatic activity this week, didn't immediately respond to the new conditions. Sustained violence in eastern Ukraine is driving a frenzy of high-level meetings in Brussels, Paris and Normandy aimed at reconciling Russia and Ukraine.
Putin is holding his first face-to-face meetings with Western leaders: Cameron and French President Francois Hollande on Thursday night, and German Chancellor Angela Merkel on Wednesday. There's hope that Putin could also talk with Ukraine's new president-elect.
Obama and Cameron spelled out new demands for Russia at a joint news conference after a Group of Seven world leader summit. Putin was meant to have hosted the summit in Sochi, but the G-7 countries cancelled that after his aggressive moves in Ukraine, and met without him in Brussels.
The US and Europe, after imposing economic sanctions on Russia in recent months, are considering toughening them.
To avoid even harsher sanctions, Cameron said Putin must meet three conditions: recognize Petro Poroshenko's election as the new leader in Kiev, stop arms from crossing the border and cease support for pro-Russian separatist groups concentrated in eastern Ukraine.
"If these things don't happen, then sectoral sanctions will follow," Cameron said. "The next month will be vital in judging if President Putin has taken these steps. And that is what I will urge President Putin to do when I meet him later today."
Obama said the G-7 leaders unanimously agree with the steps Cameron outlined. But they weren't so explicit in written statements issued after two days of meetings, and an Obama aide later described the potential sanctions in different terms than Cameron.
"If Mr Putin takes those steps, then it is possible for us to begin to rebuild trust between Russia and its neighbors and Europe," Obama said. "We will have a chance to see what Mr Putin does over the next two, three, four weeks, and if he remains on the current course, then we've already indicated that kinds of actions that we're prepared to take."