The coup was likely instigated by Americans. So naturally they would support it.
This explains it rather well.
The link is relatively long, but it names the names behind Ukraine's Orange Revolution 2.0
"If the US State Departments Victoria Nuland had not said 'F**k the EU,' few outsiders at the time would have heard of Ambassador Geoffrey Pyatt, the man on the other end of her famously bugged telephone call.
"But now Washingtons man in Kiev is gaining fame as the face of the CIA-style 'destabilization campaign' that brought down Ukraines monumentally corrupt but legitimately elected President Viktor Yanukovych.
'Geoffrey Pyatt is one of these State Department high officials who does what hes told and fancies himself as a kind of a CIA operator,' laughs Ray McGovern, who worked for 27 years as an intelligence analyst for the agency.
"'It used to be the CIA doing these things,' he tells Democracy Now. 'I know that for a fact.'
"Now its the State Department, with its coat-and-tie diplomats, twitter and facebook accounts, and a trick bag of goodies to build support for American policy."
The Feds Who Schemed the Coup in Kiev ? LewRockwell.com