LONDON – NATO members need to increase their air and missile defenses by 400% to counter the threat from Russia, the head of the military alliance plans to say on Monday.

Secretary-General Mark Rutte will say during a visit to London that NATO must take a “quantum leap in our collective defense” to face growing instability and threats, according to extracts released by NATO before Rutte’s speech.

Rutte is due to meet U.K. Prime Minister Keir Starmer at 10 Downing St. ahead of a NATO summit in the Netherlands where the 32-nation alliance is likely to commit to a big hike in military spending.

Like other NATO members, the U.K. has been reassessing its defense spending since Russia’s full-scale invasion of Ukraine in February 2022. Starmer has pledged to increase British defense spending to 2.5% of gross domestic product by 2027 and to 3% by 2034.

Rutte has proposed a target of 3.5% of economic output on military spending and another 1.5% on “defense-related expenditure” such as roads, bridges, airfields and sea ports. He said last week he is confident the alliance will agree to the target at its summit in The Hague on June 24-25.

At the moment, 22 of the 32 member countries meet or exceed NATO’s current 2% target.

The new target would meet a demand by President Donald Trump that member states spend 5% of gross domestic product on defense. Trump has long questioned the value of NATO and complained that the U.S. provides security to European countries that don’t contribute enough.

Rutte plans to say in a speech at the Chatham House think tank in London that NATO needs thousands more armored vehicles and millions more artillery shells, as well as a 400% increase in air and missile defense.

“We see in Ukraine how Russia delivers terror from above, so we will strengthen the shield that protects our skies,” he plans to say.

“Wishful thinking will not keep us safe. We cannot dream away the danger. Hope is not a strategy. So NATO has to become a stronger, fairer and more lethal alliance.”

European NATO members, led by the U.K. and France, have scrambled to coordinate their defense posture as Trump transforms American foreign policy, seemingly sidelining Europe as he looks to end the war in Ukraine.

Last week the U.K. government said it would build new nuclear-powered attack submarines, prepare its army to fight a war in Europe and become “a battle-ready, armor-clad nation.” The plans represent the most sweeping changes to British defenses since the collapse of the Soviet Union more than three decades ago.