, WASHINGTON (Reuters) - More than 20 NATO members will meet the military alliance's target of spending at least 2% of GDP on defense this year, Secretary General Jens Stoltenberg said on Monday.

Speaking to the Wilson Center thinkthank in Washington, Stoltenberg said the number of NATO allies now meeting that spending target compares to less than 10 members five years ago.

"I can only now reveal that this year more than 20 allies will spend at least 2% of GDP on defense," Stoltenberg said.

"This is good for Europe and good for America, especially since much of this extra money is spent here in the United States," he said, adding that in the last two years, more than two-thirds of Europe's defense acquisitions - or more than $140 billion - were from U.S. firms.

Stoltenberg was in Washington for preparations for next month's NATO summit in the U.S. capital and was scheduled to meet President Joe Biden later on Monday.

Stoltenberg said that when NATO leaders set the 2% of GDP target at their summit in 2014, only three members - the United States, Greece and Britain - met that target.

At that time, there were 28 members. NATO now has 32 members.

NATO defense spending has become highly contentious in recent years, particularly as former U.S. President Donald Trump has accused Europeans of spending too little on their own security and relying on the United States for protection.

Earlier this year, Trump - the presumptive Republican candidate in this year's U.S. presidential election - sparked outrage by suggesting he would not protect NATO members that failed to spend enough on defense and would even encourage Russia to attack them.

Defense spending by many European nations has risen sharply since Russia's full-scale invasion of Ukraine in February 2022 and NATO officials have been keen to stress that its European members are now stepping up to the plate.

NATO defense spending will be a major topic at next month's alliance summit in Washington, Stoltenberg said, followed by Russia's ongoing war against Ukraine.

He warned that the delay in the provision of U.S. military aid to Ukraine that occurred earlier this year cannot be allowed to happen again.

"That is why at the summit I expect our leaders to agree for NATO to lead the coordination and provision of security assistance and training for Ukraine," he said.

Noting how China has been a source of critical support to Russia but also seeks to maintain good relations with the West, Stoltenberg said, "Beijing cannot have it both ways.

"Unless China changes course, allies need to impose a cost," he said.

(Reporting by Jonathan Landay, Daphne Psaledakis and Kanishka Singh; Editing by Susan Fenton)

By Jonathan Landay and Daphne Psaledakis