North Korean and Russian nuclear weapons constitute the “primary existential threat” facing the U.S., Undersecretary of Defense Elbridge Colby told lawmakers on Tuesday, defending the Trump administration’s push for Seoul to take the lead in conventional defense planning against Pyongyang.

Colby made the remarks during a Senate Armed Services Committee hearing on the 2026 National Defense Strategy (NDS).

The 2026 NDS states that North Korea’s nuclear forces, which have grown “in size and sophistication” and pose a “clear and present danger” to the U.S. mainland, threaten South Korea and Japan with conventional and nuclear-capable missiles.

But the document released in