File: US President Barack Obama. (Reuters Photo)

US President Barack Obama said Thursday he was not about to impose new sanctions on Russia over the Ukraine crisis, but nevertheless signed a law giving him the authority to do so."The act gives the administration additional authorities that could be utilized, if circumstances warranted," the president said.But, he added, "signing this legislation does not signal a change in the administration's sanctions policy, which we have carefully calibrated in accordance with developments on the ground and coordinated with our allies and partners."Obama said his administration would continue to work closely with US allies to respond to the situation and "will continue to review and calibrate our sanctions to respond to Russia's actions."The president repeated his call for Russia "to end its occupation and attempted annexation of Crimea, cease support to separatists in eastern Ukraine."He also noted that the United States was ready to lift sanctions if Russia de-escalates the conflict in line with a prior agreement that "respects Ukraine's sovereignty and territorial integrity."Obama has said several times that he felt it was counter-productive to impose additional US sanctions without coordinating with the European Union.At a meeting in Brussels Thursday, the 28-member bloc approved sanctions on Crimea agreed on a month earlier, but did not impose any new ones as Russia sinks into an unprecedented financial crisis.French President Francois Holland said Thursday that if Russia "sends the signals we expect, then there is no need for new sanctions.""On the contrary, it would be for us to think about how we too could begin a de-escalation."

Western powers have accused Russia of stoking the Ukraine crisis, which has killed at least 4,700 people and displaced close to one million, by supplying and backing the rebels, which Moscow denies.