Winston Churchill once said that the only thing worse than fighting with allies is fighting without them. Allies are more often than not frustrating. These are especially rocky times for the United States and its relations with its NATO allies ... and not for terrible reasons.

Americans and Europeans are not cut from the same cloth. The stereotype of a European evening is drinking wine at a cafe. The stereotype of an American evening is shooting at the range.

Which is to say, Americans and Europeans have different values and temperaments, and they fundamentally view the world differently. Americans are descendants of mavericks who hated their lives so they dropped everything and moved an ocean to the New World. Europeans are the descendants of those who stayed behind and avoided taking the risk. On top of that, Europeans fought many continental wars, as recently as 80 years ago, on their soils and prefer to avoid them however they can. In contrast, the last time Americans fought a war on our own soil was the Civil War, and even then we were fighting each other. So we are generally more jingoistic than the Europeans.

And not just that. Look at our economies, how much we hate regulations, and how much Europeans love them. Look at our domestic cultures, like how we value the freedom of speech. In fact, look how much more tolerant we are. We have successfully assimilated immigrants for centuries. Europeans tried it last decade and are already regretting it. We are just different (and much better), than Europeans.

These differences in values have had serious policy ramifications. Europeans contribute little to their own defense spending. Europeans oppose us diplomatically at the U.N. Most recently, some of them even refused to let us use their bases in the war against Iran, which I will discuss in a second.

It is perfectly reasonable for President Donald Trump to be frustrated by our European allies. But also, he sometimes takes it too far. For instance, when Trump was talking about militarily annexing Greenland. I would love to have Greenland as a part of America (more so after our allies’ current passivity), and Trump was not serious about an invasion. But if a foreign leader joked about invading America, we would have already bombed them. Other nations also have a sense of national honor.

It was also a bad idea to make fun of French President Emmanuel Macron for being slapped by his wife on camera. In Trump’s defense, it was funny, and Macron doesn’t deserve any sympathy. As a former Republican official likes to recall from his time in government, every time something happened, London would call and ask how they could help us, while Paris would call to inform us that we were morons doing everything wrong and how we could help them. And that is why people love the French as much as hemorrhoids. But you never know when you need a friend.

Against Iran, Trump needed a friend, but Europeans were nowhere to be found. For weeks, the administration asked for help to reopen the Strait of Hormuz, and the Europeans said no. They would not have been so resistant if we had been nicer to them.

Going forward, the administration will serve itself much better by being nicer to our allies, especially when it is difficult. We can start by remembering something important about allies.

The most important value that an ally provides is not aggregate military power. It would be nicer if the Europeans paid more for bullets and bombs so we would not have to. But if they don’t, we still can pay to make up the difference. What we can never buy is geography, which is our allies’ most important contribution.

Let me give you an example: During the Cold War, it would take a few days for the United States to invade the Soviet Union because tanks were already parked near it. But it would take weeks for the Soviet Union to get board its tanks on ships and do a bloody amphibious landing at our shores. Ronald Reagan deployed intermediate range nuclear missiles to Germany, which would have hit the Soviet Union within minutes. But the Soviets’ counterpart missiles would have hit Germany, not America.

During the wars in Afghanistan and Iraq, we used European territories to send supplies, take our troops to receive treatments at our military hospitals in Europe, and flying mission through their airspaces.

Seventy percent of global commerce happens at sea, making maritime freedom of navigation the most important element of commerce and a key to the American people’s prosperity. The U.S. Navy upholds the freedom of navigation. This is only possible by using Navy bases in Europe. Imagine if for every refueling, repair, or rest stop, American ships would have to come back to the United States. Instead, thousands of our sailors live in Europe, and thousands more in Asia, where our allies allow us to use their territories and ports. This also makes our naval operations much cheaper.

Which brings us to Spain. Prime Minister Pedro Sanchez did not allow the U.S. military to use our bases in Spain for the war in Iran, nullifying the most important value that Spain provides to us. Trump is angry and wants to punish Spain. He is right. Spain deserves it. But if you want to punish Spain, you could use the help of the rest of Europe.

Let me give you an example. During the Iraq War, many European governments opposed our policy. But France went a step further and denied us the use of its airspace too. The whole NATO, including countries that had opposed the war, came down on France and sided with us. The Bush administration decided not to punish France harshly. It probably should have, and if it had decided so, other allies would have helped us or at least not stood in our way.

This is not a luxury we have today with Spain because of the recent diplomatic standoffs, even though Trump is right about punishing Spain.

Trump has been right about readjusting our relationship with our allies, especially regarding their defense spending. And he won that fight. They are spending much more. The stick worked. Now is the time for carrot.

Secretary of State Marco Rubio received a standing ovation at the Munich Security Conference in February. Trump and Rubio should build on that by improving the relationship. It doesn’t mean that we have to always agree with them. Sometimes we even need to air our disagreements publicly.

But we should remember that we need our allies to project power at our enemies’ doorsteps in a way that our enemies cannot project power at ours. We should also remember that there are allies who deserve to be spanked—or, in Spain’s case, flocked—and it’s much easier to spank them when nobody would defend them.

Trump has a lot of good points about our allies. He will have an easier time getting his way if he is nicer to them. Not because they deserve it, and not because he is wrong to point to our allies’ flaws, but because you’ll catch more flies with honey than vinegar.