EAST GERMAN OPPOSITION IS LAUNCHED

New Forum, East Germany's growing popular movement for reform, has begun a potentially dangerous game of political chess with Communist authorities. In just over two weeks, the group has become the most powerful unofficial force in East Germany's 40 years of Communist rule, with 4,200 signatories. Thousands marched through Leipzig Monday chanting its name.

East Berlin has responded with rhetoric and veiled threats. There has been no action to stamp out New Forum. But by branding it an enemy of the state, the interior ministry has opened up the possibility that activists could be rounded up and jailed for up to 12 years for subversion.

Western diplomats believe East Berlin is unlikely to allow the movement to flourish in the long term but think officials will probably swallow hard until the country's Oct. 7, 40th anniversary celebrations are over.