The NATO flag has been hoisted on HMS Diamond after the ship joined UK allies and partners in the Mediterranean.
The Type 45 destroyer is deployed as part of the Standing NATO Maritime Group (SNMG2).
The ship finally left Portsmouth for the deployment last month after a number of delays.
HMS Diamond's departure was originally delayed due to Storm Eunice before the Navy said the ship needed a "minor repair".
The ship was then unable to sail as it had a "technical issue".
Watch: HMS Diamond finally leaves Portsmouth for NATO mission.
The deployment comes as part of the UK's response to tensions involving Russia, before the invasion of Ukraine, bolstering European defences alongside its NATO allies.
After departing Portsmouth, HMS Diamond took part in sea trials before reaching the Mediterranean, where HMS Trent has been conducting patrols with other NATO members.