SEOUL (Reuters) -- South Korea's spy agency has observed preparations by North Korea for international inspections at several of its nuclear and missile test sites, the Yonhap news agency said on Wednesday, citing a South Korean lawmaker.

Kim Min-ki of the ruling Democratic Party told reporters the South's National Intelligence Service observed North Koreans "conducting preparation and intelligence activities that seem to be in preparation for foreign inspectors’ visit" at Punggye-ri nuclear test site and the Sohae Satellite launching ground.

The lawmaker added no major movements were seen at Yongbyon, the North's main nuclear complex.

North Korea has stopped nuclear and missile tests in the past year, but it did not allow international inspections of its dismantling of Punggye-ri in May, drawing criticism that the action was merely for show and could be reversed.

In September, its leader, Kim Jong Un, also pledged at a summit with South Korean President Moon Jae-in to close Sohae and allow experts to observe the dismantling of the missile engine testing site and a launch pad.

At the time, Moon said North Korea agreed to let international inspectors observe a "permanent dismantlement" of key missile facilities, and take further steps, such as closing Yongbyon, in return for reciprocal moves by the United States.

The U.S. State Department and Pentagon did not immediately respond to a request for comment.

Washington has demanded steps such as a full disclosure of the North’s nuclear and missile facilities, before agreeing to Pyongyang’s key goals.

American officials have been skeptical of Kim's commitment to giving up nuclear weapons, but the North’s pledge at the summit with the South drew an enthusiastic response from President Donald Trump.

In Washington, South Korean Defense Minister Jeong Kyeong-doo said the United States and South Korea would make a decision by December on major joint military exercises for 2019.

Earlier this month, the two countries suspended Vigilant Ace, one of several exercises that have been halted to encourage dialogue.

"We are not right now concerned with a loss of combat capability," U.S. Defense Secretary Jim Mattis told reporters after the meeting with his South Korean counterpart.

"Clearly as we go forward, we'll have to make adaptations to ensure we don't lose that capability. But right now, again this is not a total suspension of all collaboration and military exercises," Mattis added.