Looking for a quick way to stop North Korean missiles immediately after liftoff, the Pentagon is studying as a near-term option whether a group of F-35 fighter jets hovering around North Korean airspace could pick off freshly launched rockets.

In its current form, the idea defies physics, missile defense experts say. It calls for interceptor missiles that fly so fast they could melt, one expert said, and the only surefire way for U.S. military aircraft to defeat a missile with current technology would be to fly in hostile airspace, according to three experts.

The idea, part of a six-month study launched in January, shows how the Pentagon is seeking ways to neutralize the threat posed by Pyongyang even as President Donald Trump met North Korean leader Kim Jong Un this past week in Vietnam in his effort to stop Kim's nuclear program.