Officials in the Cabinet Office are understood to be updating the ‘homeland defence plan’ spelling out how the government would respond to a strike by a hostile foreign state.

Sir Keir Starmer has ordered a review of Britain’s war plans due to growing fears of a potential direct military attack by Russia.

Officials in the Cabinet Office are updating the ‘homeland defence plan’, detailing how the government would respond to a strike by a hostile foreign state.

The updated blueprint will include scenarios where Britain’s critical national infrastructure is targeted by missiles, cyber attacks, and even nuclear warheads.

It will also set out contingency plans for sheltering government ministers and the Royal Family, as well as maintaining key public services during wartime.

A risk assessment published in January found a successful attack was likely to result in civilian fatalities, economic damage, and disruption to essential services.

Last month, officials ran a scenario simulating the first night of Russia’s bombardment against Ukraine to test the UK’s air defences.

The wargame exposed vulnerabilities including a shortage of airfields and lack of hardened shelters, leaving bases and fighter jets unprotected.

Defence officials have called for Britain to develop its own version of Israel’s Iron Dome system to repel missile attacks.

MI5 boss Ken McCallum said the UK’s role in supporting Ukraine meant it loomed large in the imagination of Putin’s regime and should expect continued acts of aggression at home.