Donald Trump speaks at the Republican National Convention in Cleveland on July 21. (Brendan Smialowski/Agence France-Presse via Getty Images)

In his recent interview with the New York Times, Donald Trump warned that the United States would defend only NATO allies who have “fulfilled their obligations to us.” He made clear that he sees allies as business partners, and relationships with them in transactional terms: Pay up or we won’t protect you.

This framing of alliance relationships as protection-racket contracts misses the strategic value of allies to the United States. We want allies to keep the peace, fight alongside us in times of war and defend our common values — long-term strategic objectives that stretch well beyond any debate about national military budgets.

Of course we want our allies in Europe and Asia to spend more on defense. The NATO heads of state who gathered recently in Warsaw committed to doing just that. But fueling uncertainty about our security commitment to NATO in order to get the Latvians or Slovenians to increase their military budgets by a percentage point is not strategic. An alliance undermined by the loss of a credible commitment from its biggest military power quickly loses its value to everyone. Coercive statements designed to achieve short-term, marginal gains erode the most important element of deterrence — certainty of collective action in response to threats.

The United States’ greatest “return on investment” from our alliances does not come from increases in their military spending. Peace is our return, a “dividend” that produces economic and security gains for the American people.

The United States has benefited economically from peace and stability in Europe and Asia. Trade and investment with our allies in Europe over the past several decades have contributed trillions of dollars to U.S. prosperity. Peace and stability in Asia over the past 30 years also have directly fueled U.S. economic growth. You cannot “make deals” in countries that are not stable and secure.

The United States also has accrued tremendous security benefits from our alliances by avoiding war. Since the end of World War II, NATO’s success has allowed the United States to avoid sacrificing soldiers and treasure fighting in Europe. Deterrence has worked. “Peace through strength,” as Ronald Reagan championed, has worked. Why abandon this decades-long strategy now?

We don’t have to imagine what a Europe might look like without the United States credibly committed to a defensive NATO alliance. We need just remember the history of the inter-war period. Back then, when other American isolationists also were touting an “America First” slogan, power vacuums and uncertain, shifting alliances fueled instability and eventually a second world war.

In the run-up to World War II, the United States did little to engage, as politicians argued that European problems were not our concern, that dangerous fascist and communist ideologies did not affect us, and that our Depression-era focus needed to be nation-building at home. For two years, we sat on the sidelines as Hitler’s Nazi armies conquered most of the continent. Only after being provoked by a Japanese attack did we finally realize that European security directly affected our national security.

The U.S. has an "ironclad" commitment to mutual defense among the NATO allies, White House press secretary Josh Earnest said on Thursday, July 21 after Republican presidential nominee Donald Trump raised questions about whether he would defend NATO allies if they were attacked. (Reuters)

We are not on the verge of World War III today. Thankfully, destructive extremist ideologies backed up by millions-strong armies do not haunt European stability. But the lessons from that tragic chapter in European history are clear — the United States has a strategic and economic interest in a Europe “whole, free, and at peace.” When framed in strategic terms, not transactional terms, what we provide to NATO is not a burden to our economy but a direct contribution to our safety and prosperity.

In addition, our allies have contributed directly to our security since we were attacked on Sept. 11, 2001. The only time Article 5 of the NATO treaty, which declares that an attack on any member is an attack on all, has been invoked was to defend us, not one of our allies. In our common fight to defeat al-Qaeda and its ally the Taliban in Afghanistan, our NATO partners have lost more than 1,000 soldiers. Estonia was not attacked on 9/11, but Estonians went to war with us and died with us to defend our collective security goals. Americans allies South Korea and Australia also contributed to our joint military operations in Afghanistan, while another ally, Japan, has contributed billions of dollars to our shared development efforts in Afghanistan.

Our NATO and Asian allies also contribute directly to U.S. security in other ways, including by providing bases for our missile defense interceptors and radars to defend us against an Iranian or North Korean ballistic missile attack. Winston Churchill — a strategic, not transactional, thinker — had it right when he proclaimed: “There is at least one thing worse than fighting with allies — and that is fighting without them.”

Finally, it is no coincidence that our allies in Europe and Asia are also democracies. Their commitment to human rights and democratic governance means that we stand together in pushing back on autocratic states and anti-democratic movements. Trump doesn’t seem to care about democracy and human rights in foreign policy. But for the millions of people fighting for democracy and human rights around the world who do, an alliance that stands together to defend and advance these values helps their cause.

Today, our allies share more than just a transactional contract with the United States. Strategic leaders seeking to advance U.S. long-term interests — security, economic and moral — should keep it that way.