The UK Royal Air Force is set to deploy four Eurofighter Typhoon jets to Romania to deter “an increasingly assertive Russia,” the new British defense secretary has announced.

Gavin Williamson, who has recently replaced Michael Fallon as the new UK defense minister, made the announcement at his debut NATO defense ministerial meeting in Brussels on Wednesday, noting that he will commit the aircraft as part of the US-led military alliance’s southern air policing mission.

The Typhoons were first deployed to patrol the skies over the Black Sea alongside other NATO jets in May and will be sent to carry out the same mission this time alongside their Romanian counterparts, Williamson said.

The so-called air-policing mission is NATO’s response to what it calls increased Russian air activity around Eastern Europe in recent years.