With no immediate end to the Ukraine crisis in sight, senior officials from the EU, the U.S., Russia and Ukraine will try to find common ground in four-way talks next week, likely in Europe.
It will represent the first such meeting since the crisis began.
The talks were suggested by U.S. Secretary of State John Kerry, as he accused Russian forces of stirring up separatist turmoil in the eastern part of Ukraine.
He told Moscow to back down or face tougher, new sanctions that would target Russia's banking, energy, mining and arms sectors.
NATO Secretary-General Anders Fogh Rasmussen warned Russia too, saying a further intervention in Ukraine would be a "historic mistake", and that it would lead to a further international isolation for Russia.
The crisis worsened over the weekend when pro-Russian activists seized regional government buildings in three eastern Ukrainian cities.
On Tuesday, Ukraine's Interior Ministry said it had detained some 70 people during an anti-terrorist operation in Kharkiv, but that protesters are still in control of a state security building in Luhansk.
He says they are armed and holding around 60 people hostage.
Protesters occupying a government building in Donetsk have declared a "People's Republic of Donetsk" and are planning a referendum to join the Russian Republic by May 11th.
It's a potential powder keg, as the polarization of pro-Russians and pro-Ukrainians in the three cities is greater than it was in Crimea, which Russia annexed a month ago.
Kwon Soa, Arirang News.