Washington said they were prepared to use conventional weapons against North Korea if officials become convinced that North Korea is to proceed with a sixth nuclear weapons test. The US has positioned two destroyers capable of shooting Tomahawk cruise missiles in the region along with heavy bombers stationed in Guam that could provide support should such a strike should take place. 

After September 11, the US has developed a 'preemptive strike' formula for what it thinks is a threat and has shown in the past that it will not avoid using it.