Bulgaria has asked NATO to strengthen its capabilities and, at the very least, to show force on Bulgarian territory and in its territorial waters, defence minister Dimitar Stoyanov said. He has written to NATO secretary general Mark Rutte, to whom the request is addressed.

"We have asked for the full possible range – anti-drone systems, patrol aircraft," the minister explained.

Stoyanov spoke to reporters in Sofia, at the Airmen's Monument, where he took part in events marking Bulgarian Air Force Day.

He said strikes in the Black Sea are growing more intense every day. He also recalled strikes in Romania's territorial waters.

Stoyanov believes the strikes show that Bulgaria's armed forces need to be modernised.