I returned last week from the Middle East, where several colleagues and I spent the weekend meeting with leaders and security officials in Lebanon, Jordan, and Israel. As usual, the men and women who assisted us were consummate professionals-whether it was the U.S. Marines or the embassy personnel or our own military escorts and congressional staff. They all did a superb job. And I want to extend them all my deepest thanks.

I'd like to say a few words about what we learned while we were there. Contrary to the conventional wisdom, our allies told us they're more optimistic about their relationship with the United States now than they were under the last administration. Now, if you thought diplomacy consisted simply of suave sophistication, then I could understand your confusion. But among our allies, there's no confusion about what their interests are, how the United States shares them, and which country, in the whole region, threatens them the most of all: Iran. And once you realize that, it's not so hard to understand their morale boost. Do they watch what we say? Yes, of course, very carefully. But they watch even more carefully what we do.

And even though our foreign policy was cloaked in pretty words over the last eight years, they can see the difference in leadership as clear as day: The last president coddled Iran, and this president is confronting Iran.

Every conversation we had drove home this point: Iran is the single most destabilizing force in the Middle East. That's because it's more than a regional power; it's a revolutionary power. The regime in Tehran is not satisfied with finding good trading partners or even bullying other countries into the proper neighborly deference. Big countries throw their weight around all the time, after all. No, what's different about this regime is that it's not just trying to gain clients; it's trying to create clones. It wants to expand its influence by subverting legitimate governments in places like Yemen and Lebanon and replacing them with radical regimes. Countries it can't subvert, it tries to destroy, like our friend Israel. And this aggressive, sectarian ideology drives Sunni Muslims into the arms of extremist groups like the Islamic State.

There's no getting around the fact that, in the Middle East, the answer to most questions is Iran. And our allies have told me repeatedly in recent months that they need our help to confront Tehran's campaign of imperial aggression.

In Lebanon, I'm happy to say, there are signs of hope. The new prime minister, Saad Hariri, has formed a government and is reportedly on the verge of approving a budget-the first of its kind since 2005. For years, the Lebanese government has struggled with the growing influence of Iran's proxy, Hezbollah, members of which are on trial for carrying out the assassination of the prime minister's father, Rafic, in 2005. But now that Hezbollah is committed to the war in Syria, the Lebanese government has an opportunity to take control of its border, its army, and its governing institutions, free of this terrorist influence. We should take all prudent steps to support Lebanon as it strives to create security and stability, both for its own people and its neighbors.

Then there's Jordan, which for so long has been a relative island of calm in a tumultuous region. The Hashemite monarchy has been a faithful friend to America for years. But now, for the first time in recent history, Jordan faces a hostile, aggressive power on its borders-ISIS. It's also under an immense strain as it deals with hundreds of thousands of Syrian refugees living in its territory. Today, Jordan spends up to 25 percent of its budget on helping refugees. We need to continue helping this bulwark of stability stand against the forces of Islamic extremism by sharing intelligence, helping train police and counterterrorism forces, and partnering in the fight against ISIS.

And finally, there's Israel, whom it's no secret the regime in Tehran has vowed to destroy. While we were overseas, Israeli warplanes struck deep into the heart of Syrian territory. They were targeting a convoy of advanced missiles bound for Hezbollah. In a serious escalation, Syria fired missiles not only at the Israeli aircraft, but at Israeli territory-one of which was intercepted by the Arrow-2 missile-defense system.

This incident goes to show just how important our aid is to protecting Israel's security-and how important Israel is to confronting Iranian-sponsored aggression. We must continue to support Israel and its development of advanced missile-defense systems.

So I'm happy to report that all three of our allies continue to seek ever closer friendship with the United States. They're optimistic about our ability to work together, particularly under the new administration. And they sincerely appreciate everything our country has done for them.

I saw for myself a reminder of this country's sacrifice at the U.S. embassy in Beirut. There you'll find a memorial dedicated to the 241 Americans who died in the terrorist bombing of our Marine barracks in 1983. That atrocity was committed by Hezbollah, if anyone needed a reminder why we fight alongside our allies against the Iran-Hezbollah-Syria axis in the contest for supremacy in Middle East.

And if our trip taught us anything, it was that our allies won't give up the fight, but it will take American leadership to stop Iran's campaign of imperial aggression.