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Here are some more details from our news desk on Obama's comments in Washington:
U.S. President Barack Obama says the "ongoing incursion" into Ukraine by Russia will only lead to additional costs for Moscow.
The U.S. leader said Russia is training, arming and funding pro-Russian separatists in Ukraine.
Obama says new images of Russian forces inside Ukraine make that plain to see.
But he said "we are not taking military action to solve the Ukrainian problem."
Obama also said Ukraine President Petro Poroshenko will visit the White House next month.
Obama was speaking to reporters in Washington today shortly after an emergency session at the UN Security Council on the crisis in Ukraine.
U.S. Ambassador Samantha Power said Russia must "stop lying" about its invasion of eastern Ukraine and its direct military support for pro-Kremlin separatists there.
Ukrainian officials say two Russian military columns have rolled into the southeastern part of Ukraine after missiles were fired at a border post.
(AP, Reuters)