With his declaration Friday that the Iran nuclear deal is not in America’s national interest, President Donald Trump may have put us on the road to war with Iran.

Indeed, it is easier to see the collisions that are coming than to see how we get off this road before the shooting starts.

After “de-certifying” the nuclear agreement, signed by all five permanent members of the Security Council, Trump gave Congress 60 days to reimpose the sanctions that it lifted when Tehran signed.

If Congress does not reimpose those sanctions and kill the deal, Trump threatens to kill it himself.

Why? Did Iran violate the terms of the agreement? Almost no one argues that—not the UN nuclear inspectors, not our NATO allies, not even Trump’s national security team.

Iran shipped all of its 20 percent enriched uranium out of the country, shut down most of its centrifuges, and allowed intrusive inspections of all nuclear facilities. Even before the deal, 17 U.S. intelligence agencies said they could find no evidence of an Iranian nuclear bomb program.

Indeed, if Iran wanted a bomb, Iran would have had a bomb.

She remains a non-nuclear-weapons state for a simple reason: Iran’s vital national interests dictate that she remain so.

As the largest Shiite nation with 80 million people, among the most advanced in the Mideast, Iran is predestined to become the preeminent power in the Persian Gulf. But on one condition: She avoid the great war with the United States that Saddam Hussein failed to avoid.

Iran shut down any bomb program it had because it does not want to share Iraq’s fate of being smashed and broken apart into Persians, Azeris, Arabs, Kurds, and Baluch, as Iraq was broken apart by the Americans into Sunni, Shiite, Turkmen, Yazidis, and Kurds.

Tehran does not want war with us. It is the War Party in Washington and its Middle East allies—Bibi Netanyahu and the Saudi royals—who hunger to have the United States come over and smash Iran.

Thus the congressional battle to kill, or not to kill, the Iran nuclear deal shapes up as decisive in the Trump presidency.

Yet even earlier collisions with Iran may be at hand.

In Syria’s east, U.S.-backed and Kurdish-led Syrian Democratic Forces are about to take Raqqa. But as we are annihilating ISIS in its capital, the Syrian army is driving to capture Deir Ezzor, capital of the province that sits astride the road from Baghdad to Damascus.

Its capture by Bashar al-Assad’s army would ensure that the road from Baghdad to Damascus to Hezbollah in Lebanon remains open.

If the U.S. intends to use the SDF to seize the border area, we could find ourselves in a battle with the Syrian army, Shiite militia, the Iranians, and perhaps even the Russians.

In Iraq, the national army is moving on oil-rich Kirkuk province and its capital city. The Kurds captured Kirkuk after the Iraqi army fled from the ISIS invasion. Why is a U.S.-trained Iraqi army moving against a U.S.-trained Kurdish army?

The Kurdistan Regional Government voted last month to secede. This raised alarms in Turkey and Iran, as well as Baghdad. An independent Kurdistan could serve as a magnet to Kurds in both those countries.

Baghdad’s army is moving on Kirkuk to prevent its amputation from Iraq in any civil war of secession by the Kurds.

Where does Iran stand in all of this?

In the war against ISIS, they were de facto allies. For ISIS, like al-Qaeda, is Sunni and hates Shiites as much as it hates Christians. But if the U.S. intends to use the SDF to capture the Iraqi-Syrian border, Syria, Iran, Hezbollah, and Russia could all be aligned against us.

Are we ready for such a clash?

We Americans are coming face to face with some new realities.

The people who are going to decide the future of the Middle East are the people who live there. And among these people, the future will be determined by those most willing to fight, bleed, and die for years and in considerable numbers to realize that future.

We Americans, however, are not going to send another army to occupy another country, as we did Kuwait in 1991, Afghanistan in 2001, and Iraq in 2003.

Assad, his army, and air force, backed by Vladimir Putin’s air power, the Islamic Revolutionary Guard Corps of Iran, and Hezbollah, won the Syrian civil war because they were more willing to fight and die to win it. And, truth be told, all had far larger stakes there than did we.

We do not live there. Few Americans are aware of what is going on there. Even fewer care.

Our erstwhile allies in the Middle East naturally want us to fight their 21st-century wars, as the Brits got us to help fight their 20th-century wars.

But Donald Trump was not elected to do that. Or so some of us thought.

Patrick J. Buchanan is the author of a new book, “Nixon’s White House Wars: The Battles That Made and Broke a President and Divided America Forever.”