Bush Demands 'Cooperation' From Syrians
Pres Bush accuses Syria of harboring senior Iraqi military and government officials; demands 'cooperation' in punishing some of them, but stops short of threatening to use military force against Syria; asserts there are chemical weapons in Syria but does not clarify whether they were shipped there during or before war in Iraq; Syrian officials deny allegations that they are taking in Iraqi leaders and accuse Washington of waging 'disinformation campaign' to divert attention from lawlessness in Iraq; Bush also says efforts to get North Korea to bargaining table to discuss nuclear arms may be successful; question remains whether US march to Baghdad will drive North Korea to disarm or to build nuclear arsenal; Gen Tommy Franks says military has samples of Saddam Hussein's DNA and will use them to determine whether he has been killed in airstrikes (M)