WASHINGTON (AP) — America's substantial support for NATO, both in money and military aid, has long been a source of frustration for U.S. leaders, and some have questioned the organization as a throwback to the Cold War era.
Republican presidential front-runner Donald Trump, in interviews this week, suggested the U.S. should scale back its role in NATO nearly seven decades after the North American-European alliance was launched in the aftermath of World War II. Complaining that the U.S. is spending too much money on NATO, Trump said the financial burden must change.
But as attacks by extremists ripped through Brussels this week, NATO rose again as a rallying point and key player in the expanding fight against Islamic State militants. The attacks underscored the need for the U.S. and its European allies to work together to counter threats ranging from groups targeting the West to the growing Russian aggression in the region.
"Given this attack, I think you will see more willingness from NATO nations to join in the coalition in real and practical ways," said James Stavridis, the retired Navy admiral who served as NATO's top military commander from 2009 to 2013.
Trump's criticism, however, echoed persistent complaints from some U.S. leaders.
"NATO is costing us a fortune, and yes, we're protecting Europe but we're spending a lot of money," Trump told The Washington Post this week. "I think the distribution of costs has to be changed."
He did not advocate pulling out of the alliance.
The argument has dogged U.S officials for years, as they pour millions of dollars of money, troops, equipment and other infrastructure into Europe. There are about 62,000 active duty U.S. forces permanently stationed in Europe, and several thousand more rotate in and out for short-term deployments for military exercises, training and other programs.
The Pentagon has been reducing its permanent troop presence in Europe. But as the threats from Russia and the Islamic State grew, the military expanded its rotational deployments in an effort to reassure European allies and send a message to Russia that threats against NATO allies would not be tolerated.
The Pentagon has made it clear through the years that while the U.S. spends a lot on NATO, America remains staunchly committed to its European allies and is frequently dependent on them.
"The allies will never spend as much as we want them to. The trade-off is, yes, we spend more than they do, but they stand with us on these operations," said Stavridis, now dean of the Fletcher School of Law and Diplomacy at Tufts University.
He said those include operations in Afghanistan, Libya, Iraq and the Balkans, and in efforts against piracy off Africa. The allies also make up the bulk of the nations involved in the airstrikes and training operations in Iraq and Syria.
Evelyn Farkas, former U.S. deputy assistant defense secretary, said that faced with threats from Russia and the Islamic State, NATO is doing more.
"They are our allies of first resort. And in terms of return on the dollar, it's a pretty good return," said Farkas, who is a senior fellow at the Atlantic Council in Washington.
Former Defense Secretary Robert Gates delivered a brutal assessment nearly five years ago, warning that NATO faced a "dim if not dismal" future and that the U.S. would no longer carry the alliance as a charity case.
Since then, a number of European allies increased their commitment to NATO, or pledged to do so. And, faced with Russia's invasion of Ukraine's Crimea region and its support for separatists along the country's eastern border, NATO nations are participating more aggressively in their regional defense.