Stepping up its surveillance of North Korea following the recent projectile launches, the United States flew two reconnaissance planes over Seoul and its surrounding areas on Thursday.
The two American planes have been identified as an RC-135U Combat Sent and an RC-135W Rivet Joint, Yonhap News Agency reported while quoting an aviation tracker.
The latest deployment comes just five days after a US Navy EP-3E signals reconnaissance aircraft flew over Seoul.
This is being seen as an effort to detect any signs of additional military moves by North Korea after its missile firings earlier this month, following the failed second summit between the US and North Korea.
After launching multiple projectiles into the East Sea, North Korea fired short-range missiles earlier in May, inviting criticism from both South Korea and the United States.
Pyongyang, on the other hand, labelled them part of its ordinary military drills to "inspect the ability of rapid reaction" of its defence units.