WASHINGTON -- The United States' commitment to the defense of South Korea remains unaffected following the lifting of decades-old guidelines on South Korean missiles, a Pentagon spokesman said Tuesday.

John Kirby also said the removal of the missile guidelines will not lead to any change to the South Korea-US alliance.

"Nothing about this changes the alliance between South Korea and the United States or our commitments to that alliance, which...is a defensive alliance," the department spokesman said in a press briefing.

The US agreed to remove the missile guidelines in President Joe Biden's May 21 summit in Washington with his South Korean counterpart, Moon Jae-in.

First put in place in 1979, the guidelines had put limits on South Korean missiles, as well as the type of missiles Seoul can develop.

Kirby said he was "not aware of any changes" to US defense posture on the Korean Peninsula due to the lifting of the guidelines.

Washington maintains some 28,500 troops in South Korea as part of its defense treaty with Seoul, signed in 1953. (Yonhap)