The deployment last week of 15 stealth fighters to South Korea, along with the severing of the American military's only official interaction with North Korea, appears to be part of a new push by the Bush administration to further isolate North Korea despite China's hesitation to join the effort.
The deployment, confirmed by the Pentagon on Friday after several news reports, came just after the Defense Department said Wednesday that it was suspending the search for soldiers missing in action since the Korean War.
North Korea, for its part, on Sunday called the stealth fighter deployment "a risky prelude to war," a term it has often used about American military exercises.
In a change that reflects a failure of the present policy, some officials say they will no longer rely heavily on China to sway the North Koreans. Ms. Rice met with China's leaders in Beijing in March specifically to ask them to pressure North Korea. That pressure has continued. But senior officials say they now realize that China may never be willing to use its leverage over North Korea, which relies on China for much of its food, energy and other resources.