U.S. forces launched a massive retaliation Thursday against an Iranian-backed militia in Iraq—a response to a Wednesday rocket attack that killed two Americans.

This weekend, the militia struck again, wounding three Americans and three Iraqi soldiers at the very same base.

The Trump administration had promised to "restore deterrence" against Iran when it assassinated Iranian spymaster Maj. Gen. Qassem Soleimani outside Baghdad International Airport on January 3. But the army of Iraqi militias armed, trained, and advised by Soleimani is clearly undeterred: The American force in Iraq finds itself repeatedly under fire, in an escalating cycle of conflict with no end in sight.

"Restoring deterrence is not static. It is a daily habit, and you've got to get that habit as part of your system, so we every day look for ways to get Iran to go back to its own borders," Brian Hook, the State Department official in charge of Iranian affairs, had said at a February briefing.

A barrage of Katyusha rockets struck Camp Taji on Wednesday night, killing a U.S. Army soldier, a U.S. Air Force airman, and a British servicewoman. A local militia close to Iranian intelligence services called Kata'ib Hezbollah seemed to take credit for the attack in a social media diatribe invoking the "right to resist" America's "malicious project of occupation."

American forces responded with what the Pentagon calls "precision defensive strikes" against five of Kata'ib Hezbollah's weapons depots. Iraq accused the U.S. military of killing Iraqi soldiers and civilians instead of Kata'ib Hezbollah members during its Thursday air raids, aggravating already strained U.S.-Iraqi tensions.

The clashes continued, and Katyusha rockets slammed into Camp Taji again in broad daylight on Saturday. The U.S. military is now leaving some of its smaller bases in Iraq, although a spokesperson for the U.S.-led counterterrorism coalition insisted to CNN on Monday that the move has nothing to do with the latest provocations, but was "a result of the success of Iraqi Security Forces in their fight against ISIS," the Islamic State.

This weekend was not the first time since Soleimani's death that pro-Iran forces fired on U.S. troops. U.S. forces in Syria clashed with a militia aligned with Russia and Iran in mid-February, killing one Syrian, and rockets struck the U.S. Embassy in Baghdad a few days later.

Assassinating Soleimani was supposed to have prevented these attacks.

In December, a rocket killed an American translator in Iraq. (The Trump administration blamed Kata'ib Hezbollah, but the Iraqi government has since cast doubt on that version of events.) U.S. forces retaliated with a round of "precision defensive strikes" that killed 25 members of Kata'ib Hezbollah.

The Iraqi militia then incited its supporters to ransack the U.S. Embassy in Baghdad. Trump called the incident his "Anti-Benghazi," referring to the deadly 2012 attack on a U.S. consulate in Libya.

And then the President ordered Soleimani killed. Iran responded by firing ballistic missiles at a U.S. airbase in Iraq, injuring more than 100 U.S. troops, and the Iraqi parliament passed a non-binding resolution asking American forces to leave the country.

The Trump administration initially justified the assassination by claiming that Soleimani posed an "imminent threat" to American lives, but it failed to show Congress the specific threat that Soleimani posed. The administration then gradually changed its justification to "restoring deterrence" against Iran.

Soleimani "was very effective, and very lethal, and very well-networked, and so when someone like that is underway…we would have been culpably negligent had we not taken action," Hook said at the February briefing, which was hosted by the Washington-based newspaper Al Monitor.

Hook also called the Iranian government a "corrupt religious Mafia," hinting that the Trump administration does not see Iran as a state that can be reasoned with.

"I don't know how the world's leading sponsor of terrorism is entitled to a claim of self-defense. They're not at peace with their neighbors, because they don't want to be at peace with their neighbors," he said. "The regime has some of these Westphalian attributes of a state, but in fact it's got the [Islamic Revolutionary Guards Corps] and the Qods Force and the Guardian Council and all these things that exist, which are really the true nature of the regime."

Soleimani was the commander of the Qods Force, the covert arm of the Revolutionary Guards. The Guardian Council is a group of Shi'a Muslim clerics that can veto decisions by Iran's elected government.

This week, neither Hook nor Trump seemed to be very involved in the escalation. Defense Secretary Mark Esper took charge of the response to Wednesday's attack, and he signalled that he was not looking to escalate against Iran itself.

"I have spoken with the president. He's given me the authority to do what we need to do," Esper told reporters on Wednesday. "I'm not going to take any option off the table right now, but we are focused on the groups that we believe perpetrated this in Iraq."

America's military leadership has been more concerned with protecting its own personnel than opening a new front with Iran. U.S. counterterrorism forces even secretly drafted plans to withdraw from Iraq in the wake of Soleimani's death.

But without action from civilian leaders, the cycle of escalation is likely to continue. The Trump administration continues its campaign of maximum pressure against the Iranian economy, aimed at changing an array of Iran's domestic and foreign policies.

Tehran has dug in its heels, even as protesters brave bullets and tear gas to confront the state and even as a coronavirus epidemic ravages the country's infrastructure. Covert and overt support to anti-American militias in Iraq is a cheap way for Iran to strike back against the United States at a third country's expense.

For now, the cycle continues: rocket attacks, "precision defensive strikes," and the looming threat of a truly endless war.