U.S. Deputy Secretary of Defense William Lynn says North Korean intercontinental ballistic missiles (ICBM) are a threat to the U.S. homeland.

Lynn spoke at the annual U.S. Missile Defense Conference hosted by the American Institute of Aeronautics and Astronautics on Monday, stressing that U.S. missile defense should continue to focus on North Korea and Iran.

He said the United States will defend U.S. forces and allies from regional threats that continue to increase.

In a report to the White House last month, the Department of Defense said South Korea has shown interest in the U.S. missile defense network built to thwart North Korean missile attacks. Seoul has officially denied the claim.