NATO is ready to put the squeeze on its European member nations to pay their “fair burden” to preserve peace around the world, a top official said Monday.

“We expect all allies to make good on a promise made in 2014 and pay their fair burden,” NATO Secretary General Jens Stoltenberg said at a summit in Brussels attended by Vice President Pence.

President Trump argued during his presidential campaign that most of the 26 countries the North Atlantic Treaty Organization are not shouldering their fair share in the alliance, while the United States pays about 70 percent of the cost.

The countries agreed in 2014 to spend 2 percent of their gross national product on defense, but only the United States, Estonia, Greece, Poland and United Kingdom have fulfilled that commitment, according to reports.

“This must come to an end,” Pence said in a joint press conference with Stoltenberg. “The president of the United States and the American people expect our European allies to keep their word and do more.”

Though Trump suggested during his campaign that NATO was outdated and hinted that the United States no longer needs to be part of such a one-sided deal, Pence on Monday reassured the world of the U.S. commitment.

“The world needs NATO’s leadership more than ever,” Pence said. “The U.S. has a firm commitment to the NATO partnership.”

Pence praised Stoltenberg for making the fair burden issue a priority. He said that the U.S. will “continue to hold Russia accountable” for its actions, amid concerns that Trump’s efforts to improve diplomatic relations with Russian President Vladimir Putin will allow Russia to continue aggressions like those in eastern Ukraine.

Stoltenberg said there have been significant increases in NATO contributions this year.

“The good news is we are going in the right direction,” said Stoltenberg, who nevertheless said that Germany and some other European allies “have a long way to go.”