CARACAS - Venezuelan President Hugo Chávez has long been known for his harsh anti-Bush rhetoric. But now he's stepping up military plans and weapons purchases to match his combative tone, and he is worrying U.S. policymakers. Within the past two weeks the leftist populist leader has called himself a ''socialist'' and ''Fidelista,'' and offered a muscular new course for his self-described ''revolution'' on behalf of Venezuela's poor. ''I propose that we move to the offensive, just like the imperialists have moved to the bloody and ruthless offensive. If you don't believe me, look at Iraq . . .'' Chávez told...