The U.S. Navy blasted three radar installations in Houthi-held territory in southern Yemen, the first direct American intervention in the ongoing conflict there. The U.S. military is hoping that doesn’t lead to yet another war for American forces.

But hope, as the old military saw goes, is not a plan.

So far, Pentagon officials are keen to not be drawn into a broader conflict. Rather they called Wednesday’s strike a self-defense measure. But at the same time, defense officials said they were prepared to strike again, should the Houthis threaten American—or even commercial—ships in the region’s waters.

“It’s up to them,” one defense official explained to The Daily Beast, referring to whether the Houthis, Shiite-dominated rebels, attempt to strike U.S. ships again. “But it wouldn’t be smart of them to keep doing this.”

The Iranian-backed Houthis are aligned with former Yemeni President Ali Abdullah Saleh, a U.S. ally forced to step down from power in 2012. The U.S. has been providing logistical support for the Saudi-led coalition that backing Saleh’s successor, Abu Rabbu Mansour Hadi, who legitimacy has been questioned domestically. Pentagon officials concede that the region around Yemen is fragile for a cycle of strikes and counterstrikes. That is, the Saudis conduct strikes on behalf of the Yemeni government it supports—often with tragic consequences to nearby civilians. The Houthis, who consider another government legitimate, strike in response at Saudi Arabia and its American allies. And the wave of attacks start anew.

Yemen has been without a government since 2014, when the Houthis swept in and forced Hadi, the then-president, to resign.

The Houthis’ attempted missile strikes at a Navy destroyer, the USS Mason, twice in the past week appeared to be in retaliation for a Sunday attack on a funeral in Sanaa that killed at least 140 people and wounded 500 more. The Houthis hold the U.S.-backed Saudi-led coalition responsible for the air strike. On Wednesday, after the second attempt at the Mason, American forces struck back, launching three Tomahawk cruise missiles.

The Houthis, who denied launching missiles at the Mason, are already are threatening to retaliate for Wednesday’s strikes.

“The direct American attack targeting Yemeni soil this morning is not acceptable,” said Brig. Gen. Sharaf Luqman, a spokesman for Yemeni forces fighting alongside the Houthis, according to the Houthi-controlled Saba news agency. “Yemen has the right to defend itself and we would deal with any development with the right steps.”

Within hours of the attack, Iran announced that it had sent two warships to the Gulf of Aden, according to the Tasmin, the semi-official state news agency. In a statement, Iranian officials suggested the deployment of the warships had been planned long before Wednesday’s strikes.

“Iran’s Alvand and Bushehr warships have been dispatched to the Gulf of Aden to protect trade vessels from piracy,” according to Tasnim.

Pentagon spokesman Peter Cook did not offer any information Thursday about what intelligence led the U.S. to conclude the Houthis were behind the missile launches or who provided the Houthis their weapons. But, in fact, the U.S. military does have some idea about why it struck at another nation. Two defense officials believe the Houthis may have used Iranian weapons in their attempted attack on the Mason. And the radars targeted by the U.S. in retaliation were likely there long before the collapse of the Yemeni government in 2012, a second defense official told The Daily Beast.

Those Navy counterattacks may have had some help from above.

In theory, two destroyers could determine a radar’s location by triangulating the sensor’s signal, Hudson Institute analyst Bryan McGrath, a former destroyer captain, told The Daily Beast. But it’s more likely that a U.S. satellite, drone or manned surveillance plane—or Special Operations Forces on the ground—gathered the intelligence that made the retaliatory attacks possible, McGrath explained to The Daily Beast.

It’s “very difficult for the ship to do something like this without external targeting,” McGrath said.

The same forces that gathered the intelligence probably stuck around in order to assess the damage the cruise missiles inflicted, McGrath said.

Tom Cooper, an independent military analyst and author, told The Daily Beast that the Houthi missiles were probably Chinese-made C-801 cruise missiles, which are closely modeled on the deadly French-made Exocet.

The Houthis have allegedly received weapons and supplies via Iran, but it’s possible the C-801s came from former Yemeni military stocks. In 1995, the Yemeni navy acquired three attack boats armed with the Chinese weapons. The boats and their missiles could have fallen into Houthi hands as more and more of the Yemeni military defected to the Houthi side in recent years.

The Houthis could have mounted the C-801s on trucks and paired them with sea-search radars to form a kind of ad-hoc ship-killing force. “My educated guess, if you like, is that there is a unit consisting of former officers and sailors of the Yemeni navy that have sided with Houthis… and who are operating these missiles now,” Cooper said.

The attack on the Mason wasn’t the first attempted strike at a U.S. ship. On Oct. 9, after the airstrike on the Sanaa funeral, Houthi forces fired two missiles at USS Ponce, an amphibious assault ship that supports mine hunting helicopters. The Mason, which was escorting the Ponce, fired its own surface-to-air missiles, possibly shooting down one of the Houthi munitions. The other Houthi weapon fell harmlessly into the sea.

Houthi troops attacked for the second time on Oct. 12, firing at least one missile at the Mason. The destroyer fired back—and, as before, the Houthi missile struck the sea. Hours later, the destroyer USS Nitze, a sister ship of the Mason, launched Tomahawk cruise missiles at three radar installations the Pentagon suspected of helping to direct the Houthi attacks.

If the U.S Navy only managed to destroy the Houthi unit’s radars, the trucks and their missiles might still pose a threat—provided the Houthis can acquire replacement sensors. “The United States will respond to any further threat to our ships and commercial traffic, as appropriate,” Cook warned.

Critics fear that every strike and counterstrike could draw the U.S. further and further into a conflict it would rather avoid—at least directly. U.S. forces are already conducting airstrikes in Syria, Iraq, Afghanistan, and at times, Somalia.

“The rebels have long argued that American military, logistical and intelligence support for the Saudi coalition makes Washington a co-belligerent. The cruise missile strikes [Wednesday] against rebel radar sites—necessary to protect our ships in the strategic waters—will only add to the anti-American narrative,” Bruce Riedel, a former CIA analyst currently servi and current senior fellow the Brookings Institution, explained to The Daily Beast in an email.