Defence Secretary John Healey said Russia "remains the most pressing and immediate threat to Britain", and added that "any threat will be met with strength and resolve".

Britain said it monitored a Russian spy ship in the English Channel in recent days and would strengthen its response to secret operations by Russian ships and aircraft in an effort to protect undersea cables.

Putin has said repeatedly that he is prepared to negotiate an end to the war, but that Ukraine would have to accept the reality of Russian territorial gains, which are currently about 20% of its land. Kyiv meanwhile says it is not prepared to give up its territory.

In a bold move to pressure Russia into negotiations with Kyiv, U.S. President Donald Trump has issued a series of threats aimed at ending the war in Ukraine. Trump warned Russian President Vladimir Putin of imposing sanctions on Russian exports if a deal is not reached soon.

President Trump said Russian President Vladimir Putin is “destroying Russia” with its nearly three-year war in Ukraine, adding he hopes the Kremlin leader is open to making a deal to end the conflict.