Worries about a potential military conflict continue to rise on the Korean Peninsula as Pyongyang declares it is ready to conduct another nuclear weapons test at any time and the USS Carl Vinson strike group steams toward waters off North Korea.

U.S. officials continue to assert that "all options are on the table," which presumably includes a pre-emptive strike. In response, in an interview Friday, North Korean Vice Minister Han Song Ryol said "we will go to war if they choose."

In public, officials in Tokyo have welcomed Washington's tough stance. But in private, reactions are mixed.