But Mr Maduro has also been described as a pragmatist, whose achievements include a turnaround in long-strained relations with Colombia.

BBC: Profile: Nicolas Maduro

Relations between the central government and Barcelona have long been strained over issues such as devolution, distribution of revenues and local identity, and Montilla did not wish to serve up another pretext for raising tension between Catalonia and the rest of Spain.

BBC: Bullfighting in Catalonia: The death of Barcelona��s ring

In late 1988, relations between the United States and Germany were seriously strained when a long-running, secret conflict over U.S. allegations tying a German company, Imhausen, to the then-nearly complete Libyan chemical warfare plant at Rabta broke into public view.

CENTERFORSECURITYPOLICY: Center For Security Policy

He says relations with Mr Nasheed (who has a reputation for unpredictability) had long proved too strained for the coalition to hold.

ECONOMIST: Rival leaders bicker, and vie for help from India