And generally they carry out missions from Missouri and otherwise would find somewhere else to land than a Middle East Country. For example the British island south of India.The B2 is a stealth heavy bomber period. It can deliver a number of conventional weapons both "dumb" and "smart" including a payload of 16 conventional cruise missle. Combine a stealth delivery system with a stand-off munition and these can be a potent weapon with lower risk of American airmen being captured.
Their presence may have nothing to do with nukes.