A timeline of how we got here

President Trump announces that the US will formally designate the Iran Revolutionary Guard Corps, Tehran’s most powerful military institution, as a foreign terrorist organization. The move is unprecedented, marking the first time that the US designated a part of another government as a terror group. Iran responds by declaring the US a “state sponsor of terrorism.”

Tensions further escalate after attacks on oil tankers in the Persian Gulf and oil facilities in Saudi Arabia, as well as the downing of a US drone, which Washington and its allies blame on Iran. American officials repeatedly stress that threats to the freedom of navigation in the Gulf and the oil trade are unacceptable, but the Trump administration takes no action.

After the US imposes several rounds of sanctions on Iran that were originally lifted under the Iran nuclear deal, Iran announces it will ramp up enrichment of low-grade uranium. This breaks the stockpile limit it agreed to in 2015, and brings the country one step closer to being able to build a nuclear bomb.

US forces conduct airstrikes on facilities in Iraq and Syria, which the Pentagon claims are linked to pro-Iranian militias responsible for attacking US service personnel in Iraq. At least 25 people are killed, an Iran-backed militia says. Days later, hundreds of pro-Iranian demonstrators attempt to storm the US embassy in Baghdad, scaling the walls and forcing the gates open, in protest of the US airstrikes.