Students of history and those old enough to remember will recall that during John F. Kennedy's early years in office we went to the brink of nuclear war with the Soviets after they placed missiles in Cuba capable of delivering atomic warheads to American cities in mere minutes. Who would want to repeat that?
This is what happens when you have a candidate nominated by the "cut and run" crowd. You'll have bad guys all over the world, who President Bush has kept at bay, suddenly thinking now is their chance to go for it.
None of the bad guys would need to test McCain. They know what he would do and that fear deters them from acting.
An Obama presidency invites a dangerous uncertainty which threatens to disrupt peace and potentially cause war!