The Washington Post reported last month, citing unnamed officials, that the United States was moving parts of its Terminal High Altitude Area Defense (THAAD) system out of South Korea for use in its war with Iran.

The report had caused disquiet in South Korea, where the system is a pillar of national defense against nuclear-armed North Korea.

The commander of the US forces in South Korea said Washington had "not moved any THAAD systems" out of the country.

"THAAD still remains on the peninsula currently," Xavier Brunson said at a US Senate committee hearing in Washington.

"We are sending munitions forward (to the Middle East), and those are sitting right now waiting to move," Brunson said without providing further details.

Asked if he expected the system to remain in place, Brunson replied: "We do."

THAAD is designed to intercept short, medium and intermediate-range ballistic missiles using hit-to-kill technology.

South Korean President Lee Jae Myung had said Seoul was unhappy with its reported redeployment, but acknowledged there was little the government could do about it.

Seoul's defense ministry said it could deter threats from North Korea even if the United States relocated some of its military assets.

The United States stations about 28,500 troops in South Korea, and the THAAD system was installed in South Korea in 2017.

It sparked strong protests from nearby China, which viewed the system as a threat to its national security.

North Korea is showing a "very serious increase" in its ability to produce atomic weapons, the head of the UN nuclear watchdog said during a visit to Seoul this month.

The North said this week it fired multiple short-range ballistic missiles that tested the power of its cluster munitions, the latest in a flurry of launches by the diplomatically isolated state.