The American guided missile destroyer USS Mason and the amphibious transport dock USS Ponce came under attack by two cruise missiles fired from somewhere inside Yemen last Sunday.The Mason fired a whole bunch of weaponry at the attacking missiles in response, and it may just be the first time this naval defensive system has been forced to respond in the real world – and it worked.

As it stands, the U.S. military is part of a campaign with Saudi Arabia and the United Arab Emirates backing Sunni Muslims against Houthi rebels, supported by Iran, in. The incoming missiles were fired from coastal port area controlled by these rebels, but it does not appear that anyone has specifically claimed responsibility for the attack on the American vessels according to the .

As the cruise missiles screamed towards their targets, the Mason fired up its defense systems meant to knock them out of the sky.

The destroyer fired three missiles in defense in total: two SM-2 missiles and one Enhanced Sea Sparrow Missile (ESSM) to destroy the incoming ordnance, along with a Nulka anti-ship missile decoy, reported:

While the Pentagon will not confirm details of Mason’s engagement, the use of both missiles by the U.S. is, “very significant,” Bryan Clark, a naval analyst at the Center for Strategic and Budgetary Assessments and former aide to retired former-Chief of Naval Operations Adm. Jonathan Greenert, told USNI News on Monday.

“It might be the first time the SM-2 used against an actual threat for which it was designed,” Clark said.

“It’s definitely the first time ESSM has been used… This is obviously a huge deal.”

The SM-2s have been in use for decades, originally designed to defend ships against cruise-missile attacks from Russia. That’s all fine, I suppose, but none of that expensive defensive hardware has ever been used in a real engagement before. Virtually every naval engagement the United States has fought over the past few decades hasn’t really been at an adversary that was in a position to effectively fire back at American ships.

But apparently the system still works.

It’s a complicated system, too. The SM-2s are designed to counter a wide variety of threats from the air, and a significantly upgraded design, known as the SM-6, can even take down ballistic missiles in their most deadly terminal phase. The other defensive missile fired by the Mason, the ESSM, is designed to take out agile attacking missiles that skim just above the sea surface, which can make them especially hard to take down.

And then there’s the Nulka, the newest – and possibly the most innovative – system of them all. It’s essentially a rocket that can hover, but once fired off of the defending ship, it slowly moves away. All the while it has a decoy system that “projects” a ghostly radar return for another ship that isn’t actually there, leading the attacking missiles away. You can see the whole system work in action in this video released by enormous defense contractor BAE systems, or hell, just :

All of this might seem like overkill just to take down a few missiles, but it can go badly for any ship that doesn’t have these systems. Just last week the Houthi an Emirati high-speed transport vessel with a similar weapon.

Now, though, comes the question of what to do next, and the situation has become more complicated. USNI explains that while a Naval captain has unilateral abilities to defend their ship from danger, retaliation requires a lot more paperwork. The Navy is making noises about finding out who did what and responding accordingly, but it’s not so simple.

Support of the campaign in Yemen is waning with the American military brass, the Military Times says, and the upcoming American presidential election just adds to the uncertainty. But it’s unlikely that this incident, and the response to it, won’t shape the U.S. military’s longterm involvement in the region.

Editor’s note: Headline removed “Cold War” to clarify that, while this is a Cold War era concept and the SM-2 is from that time period, the rest of the technology involved in the attack is very much advanced.