(Adds comments by Nuland in paragraphs 7-10, background)
By Patricia Zengerle
WASHINGTON, April 9 (Reuters) - U.S. expectations for talks with Russia on the Ukraine crisis next week are not high, the top U.S. diplomat for Europe said on Wednesday, but it is essential to make every effort to ease tensions.
Assistant Secretary of State for Europe Victoria Nuland also reiterated the U.S. accusation that Russia was behind the takeover of government buildings in eastern Ukraine this week.
Russia, Ukraine, the United States and the European Union will hold a ministerial meeting next week to discuss the Ukraine crisis, the EU said on Tuesday.
"We don't have high expectations for these talks, but we do believe it is very important to keep that diplomatic door open," Nuland testified at a congressional hearing.
Russia said on Wednesday the four-way talks must focus on fostering dialogue among Ukrainians and not on bilateral relations among the participants.
President Barack Obama's administration has slapped sanctions on Russia and sent economic aid to Ukraine, but lawmakers have been pushing for more sanctions or other action to punish Moscow or deter further incursions in eastern Europe after its annexation of Ukraine's Crimea region last month.
Speaking at a hearing of the Commission on Security and Cooperation in Europe, known as the U.S. Helsinki Commission, Nuland said of the events in eastern Ukraine: "The evidence is overwhelming that this was a very carefully orchestrated, well-planned, well-targeted, well-coordinated effort to take over buildings in four cities within the same 24-hour period."
Nuland declined to discuss much of Washington's evidence in a public setting, but noted widespread reports on social media from Ukraine that U.S. authorities say make obvious that outsiders were involved in the demonstrations.
For example, in the eastern city of Kharkiv, the crowd first tried to take over the city opera house, before going to government buildings they intended to seize, she said.
"These were not boys from Kharkiv and they were not quite as well planned and executed as they might have been," Nuland said. (Reporting by Patricia Zengerle; Editing by Bill Trott and Mohammad Zargham)