Kerry adviser says arming Ukraine forces is an option

BERLIN (Reuters) - The United States is considering supplying arms to Ukraine, where unrest in eastern cities bears the hallmarks of a Russian destabilisation drive, an adviser to Secretary of State John Kerry said on Monday.

Ukraine's president on Monday threatened military action after pro-Russian separatists occupying government buildings in the east ignored an ultimatum to leave and another group of rebels attacked a police headquarters in the troubled region.