Britain will deploy RAF fighter jets to Poland as part of a Nato operation to counter aerial threats from Russia, the Ministry of Defence (MoD) has said.
The RAF Typhoons will join allied forces - including from Denmark, France and Germany - to reinforce Nato's defence along its eastern flank, which stretches from the Baltic states in the north to Romania and Bulgaria in the south.
It comes after Russian drones entered Poland's airspace last week, which the MoD described as a "reckless and dangerous incursion".
It prompted Latvia to temporarily close its airspace near its Eastern border with Belarus and Russia.
And in another move over the weekend, a Russian drone breached Romanian airspace.
The RAF jets will start flying missions over Poland in the coming days.
Sir Keir Starmer said Britain will continue to "ramp up the pressure on Putin".
"Russia’s reckless behaviour is a direct threat to European security and a violation of international law, which is why the UK will support Nato's efforts to bolster its eastern flank through Eastern Sentry, the Prime Minister said.
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Typhoons are equipped with advanced sensors and weapons systems
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"These aircraft are not just a show of strength, they are vital in deterring aggression, securing Nato airspace, and protecting our national security and that of our allies.
"We will continue to stand firm in our support for Ukraine and ramp up the pressure on Putin until there is a just and lasting peace."
Defence Secretary, John Healey MP, said the fighter jets will serve to "deter Russian aggression".
He said: "Russia’s actions are reckless, dangerous, and unprecedented. They only serve to strengthen the unity of Nato.
"Just as we stand with Ukraine, we will stand with our Polish Nato allies in the face of Russian aggression.
The RAF jets will start flying missions over Poland in the coming days
|MINISTRY OF DEFENCE
"The UK is fully committed to playing its part in Eastern Sentry, increasing our military presence on Nato's eastern flank even further."
Poland confirmed last week it had downed drones over its territory during a large Russian air attack on Ukraine, the first time a Nato member state is known to have fired shots in the war.
Russia's defence ministry said its drones had carried out an attack on military facilities in western Ukraine but that it had not planned to hit any targets in Poland.
The Russian drones "which allegedly crossed the border with Poland" had a range of not more than 700km (434 miles), it said.
Polish Prime Minister Donald Tusk said there was 'no need to believe we are on the brink of war' | REUTERS
Several European officials described the incursion as intentional and a sign of Russian escalation.
Polish Prime Minister Donald Tusk said it was "the closest we have been to open conflict since World War Two" but that he had "no reason to believe we're on the brink of war".
Mr Tusk said last week he had asked Nato to open consultations under Article 4 of the Washington Treaty following the incursion.
Under Article 4, discussions at the North Atlantic Council - Nato's principal political decision-making body - could potentially lead to some form of joint decision or action.
Since Nato's creation in 1949, Article 4 has been invoked seven times, most recently in February 2022 when Bulgaria, the Czech Republic, Estonia, Latvia, Lithuania, Poland, Romania and Slovakia sought consultations following Russia's invasion of Ukraine.