A British warship captured video and photographic evidence of vessels potentially violating U.N. sanctions against North Korea, the U.K.’s Ministry of Defence said on Sunday.

According to an official statement, the HMS Richmond, a Type 23 Royal Navy frigate from the U.K.’s Carrier Strike Group, conducted an intelligence-gathering mission in the East China Sea sometime earlier this month. It also tracked ships not previously known to the U.N.’s Enforcement Coordination Cell (ECC), a finding likely to spawn additional U.N. investigations later this year.