Over the weekend, President Trump inked an arms deal with Saudi Arabia worth $110 billion — the largest single arms sale in United States history. Trump's rationale is that arming Saudi Arabia will help in the fight against terrorism and help contain Iran's negative influence in the Middle East. The deal also fits Trump's "America First" vision of a transactional foreign policy centered on U.S. economic interests.

Sadly, although Trump's son-in-law and senior adviser Jared Kushner helped negotiate the Saudis a great deal, the agreement will come with a significantly higher price tag for the region and for the U.S.

The administration has yet to release all the specifics, but according to the State Department the deal would "significantly augment" Saudi Arabia's military capabilities (which were not too shabby to begin with). Land systems in the deal include tanks, armored personnel carriers, helicopters, artillery, and counter-mortar radar systems. The sea leg includes four of the new (and oft-troubled) U.S. Littoral Combat Ships, as well as patrol boats and associated weapons. The Royal Saudi Air Force will receive new transport, light close air support, and ISR aircraft. The deal will also provide missile defense systems like the Terminal High Altitude Area Defense (THAAD) system and improvements to cybersecurity and communications networks.

The biggest losers in the short run will be the citizens of Yemen. The U.S. has backed the Saudis from the beginning of the war, which has been justified by the desire to root out al Qaeda elements and curb an insurgency believed to have Iranian support.

But the cure has been far worse than the disease. Last month, the United Nations called Yemen "the largest humanitarian crisis in the world." In just three years the war has displaced millions, killed thousands of civilians, and now threatens most of Yemen's citizens with starvation and disease. Human rights organizations have documented numerous possible Saudi war crimes throughout the campaign. Trump's arms deal will allow the Saudis to escalate their attacks in Yemen, ensuring American complicity in the devastation that follows.

Longer term, this deal weakens the ability of the U.S. to advance the cause of human rights around the world. Though human rights concerns must sometimes take a back seat to security concerns, criticism from both sides of the aisle makes it clear that this is not one of those times. By failing to make human rights improvements a condition of the deal or even to raise the issue publicly, Trump's decision to sell billions of dollars of advanced weaponry to a nation with one of the world's worst records on human rights is not an example of foreign policy realism—it is an abdication of American principles.

At the strategic level the deal also fails to pass muster. By empowering Saudi Arabia, Trump believes he is combating terrorism and containing Iran. In reality, the deal will do little if anything to lower the risk of terrorism in the U.S. In fact, the deal rewards a nation that has worked hard to support the spread of the radical Islamist views that underpin Al Qaeda and the Islamic State. What the deal will do, however, is further destabilize a region already in dangerous flux thanks not only to terrorism but also to widespread civil and sectarian conflicts.

In addition to directly fueling conflict in Yemen and creating future anti-American terrorists, arming Saudi Arabia heightens tensions with Israel and raises the likelihood of an arms race with Iran. But adding more weapons to an already-fragile region won't be the catalyst for lasting peace. Only diplomacy can hope to solve the deeply rooted animosities and security dilemmas that plague the Middle East. Unfortunately, by taking sides the U.S. loses the ability to play the role of neutral broker in future diplomatic efforts.

Finally, this arms deal will help ensure that the U.S. remains entangled in the Middle East for years to come. The past 16 years of experience in the region should have taught us that American intervention to combat terrorism is of limited value, and that fighting other people's battles is a losing cause. In spite of this, Trump has enthusiastically committed the U.S. to a closer partnership with Saudi Arabia that will give many people greater reason to resent the U.S., encourage U.S. leaders to continue meddling in Middle Eastern affairs, and further destabilize the regional balance of power.

The Saudis may have given Trump a gold medal for his visit, but it's doubtful that history will do the same for this arms deal.

A. Trevor Thrall is a senior fellow for the Cato Institute's Defense and Foreign Policy Department and an associate professor at George Mason University"s Schar School of Policy and Government.

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