Britain will increase the size of its nuclear-powered attack submarine fleet, the government has announced ahead of a defense review expected to say the country must invest billions to be ready and equipped to fight a modern war.

Prime Minister Keir Starmer, like other leaders across Europe, is racing to rebuild his country's defense capabilities after United States President Donald Trump told the continent it needed to take more responsibility for its own security.

Monday's Strategic Defense Review will call for Britain's armed forces to move to a state of "warfighting readiness," spelling out changing security threats and which defense technologies are needed to counter them.

Britain will build up to 12 of its next-generation attack submarines, which are nuclear-powered but carry conventional non-nuclear weapons, to replace the current fleet of seven from the late 2030s, the Ministry of Defense said in a statement.

Britain operates a separate fleet of submarines armed with nuclear weapons. The government for the first time said a pre-existing program to develop a new nuclear warhead to replace the model used by that fleet would cost 15 billion euros.

"With new state-of-the-art submarines patrolling international waters and our own nuclear warhead program on British shores, we are making Britain secure at home and strong abroad," Defense Minister John Healey said in a statement.

The new submarines will be a model jointly developed by the UK, U.S. and Australia under the security partnership known as AUKUS.

In light of Trump's decision to upend decades of strategic reliance on the U.S. by Europe, Starmer has already committed to increasing Britain's defense spending in an attempt to reverse a long-term decline in its military capability.

He has promised to raise defense spending to 2.5 percent of GDP by 2027 and target a 3 percent level over the longer term. On Sunday he warned Britain must be ready to fight and win a war against states with advanced military forces.

In the days running up to the Strategic Defense Review, which Starmer commissioned shortly after taking office last July, the government has announced plans to spend billions on munitions plants, battlefield technology and military housing.

Juggling severely strained public finances, a slow-growing economy and declining popularity among an increasingly dissatisfied electorate, Starmer has sought to cast increased spending on defense as a way to create jobs and wealth.

Monday's review will also include building at least six new factories producing weapons and explosives, a new "Digital Targeting Web" that will help connect weapon systems and harness artificial intelligence to improve the identification and elimination of battlefield targets, and a new unit to lead its defensive cyber operations and help coordinate offensive cyber capabilities.

It will also cover advanced signal jamming and other means of disrupting communications, and improvement of the poor state of housing for the country's armed forces, seeking to help recruitment, retention and morale.

(With input from Reuters)