A US maritime surveillance plane has flown over South Korea this week, an aviation tracker said Tuesday, in the latest in a series of US surveillance operations apparently aimed at monitoring North Korea.

According to Aircraft Spots, a P-3C plane of the US Navy was spotted over South Korea on Monday.

The operation came just days after North Korea quietly marked the 72nd anniversary of its army's founding without a military parade.

"Army-Building Day," which commemorates the 1948 establishment of the Korean People's Army, is one of North Korea's biggest national holidays.

North Korea held a massive parade in 2018 showing off weapons and other military hardware to mark the 70th anniversary but quietly celebrated the day last year, which came weeks before leader Kim Jong-un held the second summit with US President Donald Trump.

Amid stalled denuclearization talks between the two countries, Kim earlier warned of a "new strategic weapon" and a "shocking actual action," saying he no longer sees a reason to stick to his earlier commitment to suspend nuclear and intercontinental ballistic missile tests. (Yonhap)