The Royal Navy vessels brought military vehicles and equipment to resupply the UK-led Nato battlegroup in Estonia, an area of “geographical interest” in the conflict.
They also conducted navigation patrols and exercises alongside ships and aircraft from six Joint Expeditionary Force nations.
The Baltic Sea is of vital strategic importance in ensuring stability and freedom of navigation in the area, especially since the war broke out.
It comes as UK personnel in Poland and Estonia was doubled to boost Nato deployment on the eastern flank of the conflict zone.
HMS Northumberland and sister ship HMS Richmond worked with warships from Denmark, Sweden, Estonia, Latvia and Lithuania to deliver Nato supplies.
A woman walks past a poster depicting Russian President Vladimir Putin holding his own body, as Russia's invasion of Ukraine continues, in Sofia, Bulgaria. Reuters
A man walks past a residential area destroyed by a rocket strike in Kyiv. Getty Images
Ukraine refugees wait in the train station in Przemysl, near the Polish-Ukrainian border. More than 3.8 million have fled Ukraine since Russia's invasion. AFP
Ukrainian civilians receive weapons training at a shooting range in Brno, Czech Republic. EPA
A Ukrainian special police officer patrols near a destroyed building during the night curfew in Kharkiv. AP Photo
A Ukrainian serviceman walks past the wreck of a Russian tank in Lukyanivka, Kyiv. Reuters
Ukrainian Air Force jets take part in a defence drill over an unidentified location. Reuters
Valentina Demura, 70, near the ruins of her home in apartment block in the besieged southern port city of Mariupol. Reuters
A message of support for Ukraine at the 94th Academy Awards in Hollywood, Los Angeles, California. Reuters
The widow of sergeant Kostiantyn Deriuhin stands at her husband's grave after his funeral at Lychakiv cemetery in Lviv, Ukraine. Reuters
A walk amid the ruins after a Russian attack in Byshiv on the outskirts of Kyiv, Ukraine. AP
A soldier of the Ukrainian territorial defence forces gives a salute during a break in digging a foxhole at Kalynivka, on the outskirts of Kyiv, Ukraine. AP
A bust adorned with a headband in the colours of the Ukraine flag at a checkpoint in Kyiv, Ukraine. AP
The Cheremosh Folk Song and Dance Ensemble performs in the streets of the Old Town in Lviv, Ukraine. Getty
Eugene Grigorash says goodbye to his wife Victoria Grigorash and their seven-month-old son Roman as their bus leaves Lviv on its way to Poland. Getty
People head for an air raid shelter after sirens sound across Lviv in Ukraine. Getty
A pro-Ukraine rally at the Lincoln Memorial in Washington. EPA
The aftermath of an air strike on the western Ukrainian city of Lviv. AFP
A protester weeps as she takes part in a 'mothers' march' for Ukraine, in New York. AFP
Local people share a basement of a historical building which is being used as a bomb shelter during an air raid warning in Lviv. EPA
US President Joe Biden kisses a child while meeting refugees of Russia's war with Ukraine at PGE Narodowy Stadium in Warsaw, Poland. AFP
A Ukrainian soldier stands guard at Independence Square in Kyiv. AFP
Municipal employees cover the city's monuments with sand bags to protect them from strikes in Kharkiv. AFP
Misha, 5, who lost his mother some weeks ago and got injured during a Russian strike, is helped by his grandfather to dress up in the basement of a hospital in Mykolaiv. AFP
Ukrainian refugees rest in the ticket hall of Przemysl Glowny train station. Reuters
A woman walks past destroyed houses in the village of Krasylivka outside Kyiv. Reuters
A man climbs up a ladder to examine his destroyed house in the village of Krasylivka outside Kyiv. Reuters
Damage inside an Orthodox Church building in Yasnohorodka, on the outskirts of Kyiv. AP
A Ukrainian soldier at a psychiatric hospital damaged by a Russian bombing, in Mykolaiv. AP
Displaced people from Dnipro arrive in Lviv, in western Ukraine. Millions are internally displaced. Getty Images
A destroyed school in Kharkiv. AFP
A Ukrainian fighter on the front line in the north Kyiv region. Reuters
A resident walks past blazing buildings and vehicles after a Russian artillery strike in Kharkiv. AFP
Black smoke billows from a fuel depot near Kyiv that was used by the Ukrainian Army before it was hit by during a Russian strike. AP
Masha, 26, checks her mobile phone at an air raid shelter inside a Kyiv metro station. Reuters
A market on fire in Kharkiv after a Russian attack. AP
People try to recover items from a shop set on fire during a Russian attack in Kharkiv. AP
Nastya Kuzyk, 20, who was injured in an attack on Chernihiv, is comforted by her mother Svitlana, 50, as she recovers in a Kyiv hospital. AP
The UK’s new RAF Poseidon P8A submarine hunter aircraft practised working with the ships to spot enemy vessels.
“Activities such as these in the Baltic Sea are routine business for us and our JEF partners, in one of our principal areas of geographical interest,” said Maj Gen Jim Morris, commander of the UK Standing Joint Force HQ, which leads the JEF.
“Given the current level of aggression being displayed by Russia, there has never been a more important time to ensure that freedom of navigation is maintained in the Baltic Sea.”
This browser does not support the video element.
“Our short but intense period in the Baltic Sea has seen Richmond integrate with a number of JEF nations and I have been highly impressed with the adaptability and professionalism of the ship’s company,” said Chris L’Amie, the commanding officer of HMS Richmond.