Sen. Rand Paul is not happy with President Trump’s decision to send more troops to Saudi Arabia.

“It's inconsistent to say we're not going to be [in the Middle East] for endless, senseless wars and then to [send U.S. troops to defend] Saudi Arabia,” the Kentucky Republican charged on Meet the Press on Sunday. But inconsistency isn’t the only problem with the Trump administration’s decision over the past month to send an additional 3,000 Americans to defend Saudi Arabia — there’s also a grave risk of all-out war and other unintended consequences.

In fact, Paul continued , “One of the things that [Osama] Bin Laden said motivated him [to attack America] — it's not a justification, obviously; it was terrible, and he got what he deserved — but one of the things he said that motivated him were [U.S.] troops in what they considered to be [Islamic] holy land. And so I think having troops in Saudi Arabia becomes a magnet for all the crazy jihadists around the world to motivate them to attack again.”

Trump should heed Paul’s warning.

Examining the motives of those who commit monstrous attacks on innocents is always uncomfortable, and of course U.S. foreign policy can’t be dictated by the feelings of our enemies. But it is dangerous and delusional to send our troops into harm’s way without bothering to predict the likely results. No responsible strategist would risk soldiers’s lives without a careful analysis of the unintended consequences of deployment.

And the risk of grave unintended consequences from this deployment to Saudi Arabia is real. The placement of U.S. troops in Saudi Arabia prior to 9/11 was a major recruiting point for bin Laden’s al Qaeda network, and there is no reason to think their presence will not be used the same way again, even if it’s another radical group under a different name. Refusing to acknowledge that reality is shortsighted and careless. It also prioritizes Saudi Arabia’s interests at the expense of our own.

But the chance of bolstered terrorist recruiting is not the only hazard here.

Pledging U.S. military might to Saudi Arabia’s defense is likely to escalate regional tensions and embolden Riyadh to double down on its reckless, counterproductive foreign policies. It heightens the stakes in the Saudi rivalry with Iran, a stubborn clash built on centuries-long religious conflict. Washington’s involvement encourages Saudi Arabia and Iran alike to behave more aggressively, one confident in U.S. backing and the other determined to show it will not be cowed by the same. Deploying U.S. forces to Saudi Arabia makes regional war more likely, not less.

A third unwanted externality is the further marginalization of Congress from its constitutional role in setting our foreign policy. Washington’s unconditional support of Saudi Arabia is a project of executive war-making in explicit contradiction of the Constitution’s design.

Earlier this year, Trump made rare use of his veto power to shoot down a bill that would have ended U.S. support for the brutal and chaotic Saudi-led intervention in Yemen’s civil war. He likewise ignored bipartisan resolutions disapproving of arms sales to the Saudi government.

This new act of military support for Saudi Arabia is one more step down the treacherous path of unaccountable, and strategically bankrupt, foreign policy. Trump should swerve off this risky course before these unintended consequences make Americans less safe and further erode our prosperity.

Bonnie Kristian is a fellow at Defense Priorities and contributing editor at the Week.