Washington: US President Barack Obama and British Prime Minister David Cameron spoke by telephone Wednesday, the eve of a meeting of European Union leaders on how to respond to Russia`s incursion into Ukraine.
Obama spoke to the British leader as he traveled to Connecticut on Air Force One, and both men agreed Russia`s action had violated Ukrainian sovereignty, the White House said in a statement.
"Russia has already started to pay a cost for its actions, such as reducing investor confidence in Russia," the statement said, adding that the allies backed the Organization for Security and Cooperation in Europe (OSCE) military observer mission to Ukraine.
A Downing Street spokesman said Cameron and Obama noted that while there had been no serious escalations by Russia in the last 48 hours, the situation remained unacceptable and Russian troops had yet to return to their barracks in Crimea and that the peninsula remained "extremely tense."
European leaders will debate an aid program for Ukraine at a special summit in Brussels on Thursday.