North Korea has threatened to inflict “unforeseen disaster” on the U.S. over its deployment of a reconnaissance aircraft to monitor its activities, warning that such “hostile” acts will lead Pyongyang to further accelerate military development.

In a commentary released on Friday, the state-owned Korean Central News Agency (KCNA) accused Washington of carrying out “air espionage” using an RC-135U aircraft that took off from Japan two days earlier.