Investigators on Tuesday raided the spy agency and a military intelligence command among other locations over suspicions related to alleged drone flights to North Korea, officials said.

Axar.az informs, citing Yonhap, a joint team of police and military investigators executed search-and-seizure warrants at the National Intelligence Service, the Defense Intelligence Command and 16 other locations as part of its investigation into the alleged flights.

The joint investigation was launched last month after North Korea claimed South Korea infringed on its sovereignty with drone incursions in September and on Jan. 4.