Inside the Houthis’ Stockpile of Iranian Weapons

Since they first began launching missile and drone attacks at commercial ships to protest the Israeli military offensive in Gaza last November, the Houthis in Yemen have drastically cut maritime trade in the Red Sea, a strategic global trade chokepoint. Since Nov. 19, there have been at least 30 attacks on ships in the Red Sea, of which 13 suffered direct drone or missile strikes.

U.S. and British strikes on Houthi military targets, which began on Jan. 11, have degraded the Houthis’ arsenal, but they haven’t stopped or even slowed the group’s attacks so far. (The attacks have proved to be a massive boon for the Houthis’ reputation and credentials both internally in Yemen and in the region, amid a groundswell of anger at the high civilian casualty toll in Gaza.)

The two big questions. There are two major questions on everyone’s minds in Washington as they scramble to deal with this crisis. The first is how much damage the Houthis can do. The second is how long they can keep it up.

On the economic side, a lot of damage has already been done. The Houthi attacks have sent shockwaves through the global economy as maritime shipping companies reroute their container ships to avoid the Red Sea. Maritime trade through Egypt’s Suez Canal, the waterway connecting the Mediterranean Sea to the Red Sea, dropped 42 percent in the previous two months, a top U.N. official warned last month, putting new strains on global food supply chains as Africa and Asia rely on European food staple exports through the sea. There’s also a nagging new fear that the Houthis, or their backers in Iran, could turn to targeting undersea cables in the region that carry nearly all the data and financial communications between Europe and Asia, as our colleague Keith Johnson reports this week.

Then there’s the risk of the conflict spiraling. Neither the United States nor Iran want these limited proxy conflicts to turn into an all-out war. But that doesn’t take a major escalation, through a lucky Houthi strike or a miscalculation, off the table.

So far, U.S. warships in the region have been able to shoot down all Houthi missiles and drones that have come near them—including one particularly close call last week—but one lucky strike by a Houthi salvo that causes U.S. casualties could dramatically escalate the conflict. U.S. President Joe Biden would certainly face a groundswell of political pressure, particularly from Iran hawks, to launch a devastating response if Houthi attacks caused any U.S. casualties or struck U.S. warships.

So, how long can the Houthis keep this up? The United States and Britain have so far conducted three rounds of joint strikes in Yemen targeting the Houthis’ military arsenal—the Biden administration has approved several more unilaterally—and the U.S. and British militaries have been open about what they’ve hit. In the latest strike, for instance, the U.S. military announced that on Wednesday night, it took out two Houthi mobile anti-ship cruise missiles ready to launch and about two hours later made a second strike against a Houthi mobile land attack cruise missile that was on the launchpad.

But there’s still a lot we don’t know. Notably, no Western government has been open about estimates of how many missiles and drones the Houthis have left. And that precise information is very hard to come by if you don’t have a security clearance. (We don’t.)

A new intelligence report sheds some light. The U.S. Defense Department’s intelligence arm is out with a new unclassified report this week detailing just what’s in the Houthis’ arsenal—most of it tech that can be linked back to Iran. This includes unmanned aerial vehicles (UAV) that act as remote suicide bombers. The Houthis claim their Sammad one-way attack UAV has a range of more than 1,100 miles and can carry a payload of around 45 to 110 pounds. (The Sammad looks almost identical to an Iranian drone model called the Sayad, or KAS-04.)

The longest-range drones that Iran has given the Houthis have the ability to strike targets as far as 1,500 miles away, potentially putting almost all of the 30,000 U.S. troops now based in the region at risk.

Since 2015, as the defense intelligence report notes, Iran has provided the Houthis with an arsenal of short- and medium-range ballistic missiles, including the Asif anti-ship ballistic missile that has been lobbed at targets in the Red Sea and the longer-range Toofan ballistic missile (which bears a remarkable resemblance to Iran’s Shahab-3 medium-range ballistic missile).

There isn’t much publicly available information on the precise size of the Houthis’ arsenal, but their yearslong civil war against Saudi-backed forces in Yemen provides at least a partial glimpse into this question. Between 2015 and the end of 2021, the Houthis launched 851 UAVs and 430 rockets and ballistic missiles against Saudi targets, according to data from the Saudi armed forces.

Yes, but… There are two things to keep in mind, though. The first is that while the Houthis’ supplies aren’t limitless, the group has already shown it can do a lot of damage with just a limited number of strikes. Even an arsenal of a few dozen missiles and a few dozen drones can keep up pressure on trade in the Red Sea, and on the U.S. Navy patrolling it, for months to come.

The second is that, as we said, the Houthis have been engaged in a war for eight years against the Saudi-backed government in Yemen—and have maintained their arsenal under years of Saudi airstrikes. And unfortunately for the United States and its allies, the group has gotten pretty good at it.

“We have the Saudi track record to look at,” said Ali Vaez of the International Crisis Group. “Eight years of trying to degrade Houthi capabilities and prevent them from replenishing their weaponry with strict embargoes—it didn’t work,” he added. “We can repeat the same experience over and over again and expect a different result, but it’s hard to imagine that changing.”

In short, the game of Houthi strikes and U.S. and British counterstrikes doesn’t have any end in sight yet.