How we understand history—the past as well as how the present will become the past—is determined by when we start the clock. The skyrocketing crisis between the United States and Iran didn’t start a few days ago when rockets fired at an Iraqi military base killed a US military contractor. (US officials claim that the rockets were fired by Khataib Hezbollah, an Iraqi militia with ties to Iran; the militia denies the claim.)

It didn’t start when the United States retaliated with a major attack on the militia, killing at least 25 of its forces. It didn’t start when supporters of the militia as well as many other Iraqi protesters demonstrated outside and attacked the perimeter of the US embassy in Baghdad’s heavily fortified Green Zone.

And it didn’t start when the Pentagon escalated further, at the direct order of Donald Trump, to assassinate Iranian Maj. Gen. Qassim Suleimani yesterday with a drone strike on Baghdad’s international airport. The commander of Iran’s Islamic Revolutionary Guard Corps’ Quds Force, Suleimani was the main coordinator of Iran’s strategic alliances across the Middle East, and a revered and highly honored political and military figure among the Iranian population.

This crisis began almost two years before, when Trump abandoned the internationally endorsed nuclear deal with Iran. Tehran was complying with the agreement, and the diplomacy had succeeded in preventing Iran from moving toward production of a nuclear weapon and was allowing the Iranian people at least a modicum of relief from crippling economic sanctions. Trump’s decision to walk away from the deal, launch an economic war in the form of new devastating sanctions, and announce a policy of “maximum pressure” against Iran set the stage for the dangerous escalation we are seeing right now.

Iraqi militias backed by the Quds Force have long operated in Iraq, with many of them, including the Khataib Hezbollah, functioning as part of Iraq’s military and security institutions even while being supported by Iran. That shouldn’t have been surprising—it was consistent with Iran’s long-standing ties to and support for the Shi’a-dominated government put in place by the United States in Baghdad following its 2003 invasion and occupation of Iraq. But Iran’s role was as complicated as the war itself.

During the long years of the Iraq War, some Iranian-backed Iraqi militias played significant roles in the resistance to the US occupation, including in attacks that killed and injured US troops. But the Iraqi government, kept in power by the United States, maintained strong ties to Iran. And in 2014, when ISIS forces commandeered huge swathes of Iraqi territory and US troops were redeployed back to Iraq, the US and Iran found themselves fighting on the same side, against ISIS (too often with Iraqi civilians paying the highest price).

The Trump administration reportedly notified Israel, Saudi Arabia, and the UAE, its key regional allies, before striking Iraqi militia bases on Sunday—but the United States did not notify the Iraqi government, its supposed ally whose territory it was about to attack. Iraqi Prime Minister Adel Abdel Mahdi called the attack a violation of his country’s sovereignty. There is no indication that Washington informed Iraq about its intention to send armed drones to attack the Baghdad airport and assassinate the Iranian military leader 24 hours later.

Tensions have been rising between the United States and Iran since Trump’s withdrawal from the nuclear deal. Despite some of Iran’s challenges to the US and its allies in the Persian Gulf, Iran has made clear that it does not want to escalate to all-out war with the US or its regional allies, including Israel or Saudi Arabia. The US policy of “maximum pressure,” which the administration imposed after abandoning the nuclear deal, relies on economic sanctions hurting the people of Iran, as well as US military threats and feints just short of direct military attack.

The threat of “accidental” escalation, which wouldn’t be accidental at all, still loomed.

Then came an attack on the Iraqi base that killed the US military contractor—it’s still not known who actually carried it out, but Washington is holding Iran responsible. Following that, the United States killed at least 25 Iraqi militia troops backed by Iran, and now it’s acknowledged responsibility for the assassination of one of Iran’s most powerful—and publicly popular—leaders. The Iranian leadership will clearly be under domestic pressure to respond forcefully to Suleimani’s assassination—and with Iran essentially surrounded by US-backed governments and major US military installations, they have a plethora of potential targets. The real question will then be, how will the Trump administration respond to Iran’s inevitable payback?

The US escalations—including the attack on the Iraqi militia and the assassination of Suleimani—were carried out without congressional approval. The current presence of US troops in Iraq has not been authorized by Congress at all—and even the White House’s justifications for deployment were based on claims of fighting ISIS, not launching attacks that could lead to war with Iran.

The urgent need right now is for Congress and the people of the United States to demand a stand-down from Washington’s belligerence toward Iran. We need diplomacy, not war. The clock is ticking.