On Wednesday night, U.S.-led coalition forces based out of Camp Taji north of Baghdad came under intense rocket fire. The attack killed three coalition personnel, two American and one British. It also injured nearly a dozen more personnel.

While rocket fire on U.S. military bases in Iraq is not new, this attack is the first time U.S. personnel have been killed by suspected Iranian-backed Iraqi groups since the United States killed Iranian Gen. Qasem Soleimani in early January. The attack is likely to anger the Trump administration, which has pursued an aggressive strategy against Iran. It also catches the White House in the middle of another ballooning international crisis — the coronavirus pandemic.

Why did this attack happen now? And will this incident spark more hostilities in the Middle East?

Iran’s calculus

While no group has claimed responsibility, the U.S. military believes Iraqi militia groups backed by Iran launched the attack. The attack involved around 18 small Katyusha rockets — weaponry Iranian-backed militias commonly use. The target of the base, Camp Taji, has previously received fire from militias in Iraq. Furthermore, given the risks involved for Iran and its allies in facing U.S. retaliation, this attack is unlikely to have occurred without Iranian approval or guidance — especially as any rogue action would put Iran at risk.

Given Iran’s likely involvement, some may view this attack as more Iranian retaliation for Soleimani’s slaying. In early January, ballistic missile attacks on U.S. positions in Iraq failed to kill any Americans or significantly damage U.S. interests in Iraq. But to view this attack only as revenge misses the larger political and strategic context.

Since 2018, the Trump administration’s “maximum pressure” campaign has sought to economically squeeze Iran over its nuclear program. Iran has responded with an asymmetric strategy of ramping up costs for the United States in Iraq, mainly through intermittent small-scale violent attacks by various allied militias. The goal is to start by limiting U.S. room to maneuver and eventually to compel it to leave Iraq entirely. This most recent attack aligns with that approach.

What’s more, Iran is likely responding to other factors than the Soleimani slaying. For example, since October, Iraq has been ensnared by a domestic political crisis, with a protest movement calling for reforms and new leadership. Recently, Prime Minister-designate Mohammed Tawfiq Allawi failed to form a government. Iraqi President Barham Salih appears to be preparing to next appoint current Iraqi intelligence chief Mustafa Kadhimi, giving him the chance to forming a new government. Kadhimi is considered a U.S. ally, opposed to the interests of the militia parties backed by Iran.

To prevent that outcome, Iran and its allies may be trying to force a U.S. military response on Iraqi soil, hoping to regalvanize anti-U. S. sentiment. That would jeopardize Kadhimi’s ascension. The current caretaker prime minister, Adel Abdul Mahdi, would probably remain in power — as Iran and its Iraqi allies would prefer.

Further, the United States and the Iraqi government are in ongoing negotiations about allowing the deployment of U.S. Patriot surface-to-air missile defense systems on Iraqi soil. Those would obviously be used to fend off Iranian missile strikes against the U.S. presence in Iraq — and would change the strategic balance between the two. A defense system that shields U.S. personnel from another ballistic missile attack would make American personnel less vulnerable in Iraq, giving its military more flexibility to counter Iran in the region. From Iran’s perspective, a missile defense system would enable future U.S. aggression.

How can the U.S. respond without setting off a war?

Wednesday’s attack on Camp Taji revives the United States’ strategic dilemma on responding to Iranian aggression. How can Washington retaliate without making itself more vulnerable in the Middle East? On the other hand, President Trump may have a strong urge to act, given his pledge to retaliate if Americans are harmed. Joint Chiefs Chairman Gen. Mark A. Milley also announced that response “options are on the table.”

What options might the United States consider? A mild response could involve doing nothing militarily, responding instead with heightened economic sanctions. Stepping it up a notch, the United States could hit Iranian proxies with airstrikes in peripheral regions of Iraq, such as the Iraq-Syria border. Such an attack may hurt Iran but minimize the risk of escalation. Escalating even more could involve again targeting someone significant, as with the drone killing of Soleimani and Abu Mahdi al-Muhandis, Iran’s top Iraqi militia ally, near the Baghdad airport. Or the United States could launch airstrikes on Iranian soil — which may well bring Iranian retaliation and push the situation toward war.

There are two reasons the United States isn’t likely to go all-out in its response. First, Trump is distracted by the escalating coronavirus pandemic, which has hurt the U.S. and global economy. Any major military action that undercuts stability in the Persian Gulf would further rock the global economy. As Trump is keen on limiting economic losses, he may take seriously the probable economic implications of any military undertaking against Iran.

Second, his key advisers — such as CIA Director Gina Haspel, who supported the strike against Soleimani — may not favor escalation. Iraq’s domestic politics are precarious — as is Iraq’s appetite for a continuing U.S. military presence. The United States has threatened Baghdad with sanctions if the Iraqi government were to kick out its troops — and appears keen to keep its military based in Iraq.

But of course, there’s no predicting what Trump will do. It’s not clear whether he will correctly judge the stakes and risks with Iran, atop the pandemic crisis.

Asfandyar Mir (@asfandyarmir) is a postdoctoral fellow at the Center for International Security and Cooperation at Stanford University.

Ramzy Mardini (@RamzyMardini) is a USIP-Minerva Peace Scholar at the U.S. Institute of Peace and a PhD candidate at the University of Chicago.