State Department spokeswoman Jennifer Psaki rejected suggestion of arms aid by the agency's counselor Thomas Shannon, saying Washington was focusing on its "economic and diplomatic efforts."

　　"We don't see a military solution to this crisis, and that hasn 't changed," Psaki told reporters at a regular news briefing. "Our focus is not on military assistance or a military solution."

　　White House spokesman Jay Carney also said the administration was not "actively considering lethal aid."

　　Shannon said in Berlin earlier in the day that the Obama administration was looking at arms supply to Ukraine "as an option " though he was not sure of the outcome.

　　Pro-Russia protesters, riding on a new wave of unrest that erupted in eastern Ukraine on April 6, took control of several government buildings in eastern Ukraine over the weekend and refused to heed Kiev's ultimatum to leave by Monday morning.

　　Ukraine's acting President Oleksandr Turchynov has vowed to launch a "large-scale anti-terrorist operation" against the armed militants, while Russia, which has massed troops on the border, has repeatedly warned Kiev against using force to restore order.

　　Both Psaki and Carney confirmed that John Brennan, director of the U.S. Central Intelligence Agency, was in Kiev over the weekend.

　　"There were some claims that Director Brennan encouraged Ukrainian authorities to conduct tactical operations inside Ukraine," Psaki said. "Those are completely false."

　　Earlier in the day, U.S. President Barack Obama and his French counterpart Francois Hollande spoke over the phone of the " worsening situation" in eastern Ukraine, "where pro-Russian separatists, seemingly with support and coordination from Moscow, have intensified their campaign to undermine and destabilize the Ukrainian government," the White House said.

　　"The leaders underscored that Russia will face significant additional costs if it continues this behavior," the White House said in a readout of the phone talks.

　　Washington has threatened to target Russia's key sectors of economy like energy, banking and mining in response to its further moves against Ukraine.

　　It has suspended military cooperation and trade and investment talks with Russia, and slapped sanctions on a number of key Russian and Crimean officials as well as a Russian bank, in response to Russia's annexation of Crimea from Ukraine last month.

　　The U.S. on Monday signed a one-billion-dollar loan guarantee for Ukraine, part of an aid package in support of the country's economic recovery.

　　U.S. Vice President Joseph Biden will travel to Kiev on April 22.