In the bipolar international system of the Cold War, nations took their cue on nuclear matters from the two superpowers.

CENTERFORSECURITYPOLICY: Center for Security Policy | Fumble on the Test Ban Treaty By Richard Burt The Washington Post, 18 October 1999

And there is indeed a sense of movement towards bipolar politics and a system of alternating governments.

ECONOMIST: Romano Prodi, Italy��s would-be record-breaker

He should urge the creation of a new electoral system that would bring about a more bipolar parliament, less in hock to the whims of small parties.

ECONOMIST: Carlo Azeglio Ciampi, Italy��s new president