Türkiye has prevented two UK Royal Navy minehunter ships donated for Ukraine from accessing its waters on their way to the Black Sea, citing a breach of an international pact regarding wartime straits passage, according to Daily Mail.

This move comes after last month’s UK announcement of the transfer of the ships to Ukraine to bolster its naval capabilities in the ongoing war with Russia. Türkiye, a fellow NATO member, has informed allies that it will deny passage through the Bosphorus and Dardanelles straits as long as the Russo-Ukrainian war persists.

Britain pledged to send the ships to Ukraine last year, and as of last August, Ukrainian sailors were in the UK, training on the vessels as part of a program to possibly transfer up to nine of such ships.