The Ukraine Crisis: 15 Words You Need to Know

They were also encouraged by his seeming acceptance of elections in May as a way to legitimize a new Ukrainian government and by his decision to cancel a military exercise near the border.

For all his bluster and bravado, President Vladimir V. Putin’s assurance on Tuesday that Russia does not plan, at least for now, to seize eastern Ukraine suggested a possible path forward in the geopolitical crisis that has captivated the world.

For all his bluster and bravado, President Vladimir V. Putin’s assurance on Tuesday that Russia does not plan, at least for now, to seize eastern Ukraine suggested a possible path forward in the geopolitical crisis that has captivated the world.

Even if Russia does leave eastern Ukraine alone and avoids escalating its military intervention, can it effectively freeze in place its occupation of the Crimean Peninsula?

And they detected no new influx of troops into Crimea.

The administration is developing plans for actions that would escalate over time if Russia continued to leave forces in place in Crimea, an autonomous region of Ukraine.

Mr. Obama could also sign an executive order creating another set of sanctions specifically against Russian officials and organizations blamed for creating instability in Ukraine and violating its sovereignty.

Still, others are more dubious, noting that Mr. Obama may not be willing to go as far as necessary without the support of allies, particularly given that it would presumably jeopardize Russian cooperation on a range of issues, including Syria, Iran, Afghanistan and Middle East peace.

Their first priority is preventing Russia from annexing the peninsula outright, but even leaving it as an enclave under Moscow’s control would not be acceptable, they said.

But the development presented a tricky conundrum for President Obama and his European allies.

Even if Russia does leave eastern Ukraine alone and avoids escalating its military intervention, can it effectively freeze in place its occupation of the Crimean Peninsula?

Ever since Russian forces took control of Crimea, Mr. Obama’s aides have privately conceded that reversing the occupation would be difficult, if not impossible, in the short run and focused on drawing a line to prevent Mr. Putin from going further.

If Crimea in coming weeks remains cordoned off, it will then require a concerted effort to force Russia to pull back troops, an effort that could divide the United States from European allies who may be more willing to live with the new status quo.

While Secretary of State John Kerry visited Kiev on Tuesday to show support for its beleaguered pro-Western government, Mr. Obama consulted with Chancellor Angela Merkel of Germany by telephone about finding a face-saving way for Mr. Putin to withdraw in favor of international monitors.

He said Crimea would become a precedent: “Crimea is a big deal. It means a country can be invaded, and a big piece of it can be taken away with no price. But two, this isn’t just about Crimea. This is about who is ultimately in control of Ukraine.”