An attack using an explosives-packed drone on an airport in Arbil, capital of Iraqi Kurdistan, is the latest in a series targeting Western military or diplomatic installations on Iraqi soil since late 2019, and marks an escalation of the weapons used.
A US-led international coalition has been in Iraq since 2014 to help local forces fight the Islamic State jihadist group.
Here is a summary of the attacks:
Repeated mortar and rocket attacks target American interests in Iraq from October 2019.
No one claims responsibility, but Washington blames pro-Iran factions.
A US civilian contractor is killed on December 27 when around 30 rockets are fired at the K1 Iraqi military base in Kirkuk, an oil-rich region north of Baghdad.
Two days later the US bombs a military base in western Iraq where Kataeb Hezbollah, a hardline Iraqi military faction close to Iran, is based. At least 25 fighters are killed.
US embassy stormed
Pro-Iran protesters storm the US embassy compound in Baghdad on December 31, 2019, expressing fury over US strikes.
A mob lights fires and chants “Death to America!” before withdrawing a day later.
US kills commanders
Tensions between Iran and the US peak in January 2020 following a US drone strike at Baghdad airport that kills Iranian general Qasem Soleimani and top Iraqi paramilitary commander Abu Mahdi al-Muhandis.
In retaliation, Iran launches a volley of missiles at two Iraqi bases housing US and other coalition troops, wounding dozens.
Two months later, on March 11, a rocket kills two American soldiers and a British soldier, the deadliest rocket attack in years on an Iraqi military base hosting foreign troops.
In response, air strikes kill 26 pro-Iran Iraqi paramilitaries on the Syrian border.
Over the year, dozens more rockets and roadside bombs target Western security, military and diplomatic sites across Iraq — some of them deadly.
After a threat by the US to close down its embassy in Baghdad, Iraqi hardline groups agree to a truce in October 2020.
There are intermittent violations, including a volley of rockets that explodes near the US embassy on December 20.
In the period since US President Joe Biden took office at the end of January 2021, some 20 bomb or rocket attacks have been launched.
In one attack — days before Pope Francis visits Iraq in March — rockets slam into Ain al-Assad base in the western desert, leaving one civilian contractor dead from a heart attack.
On February 15 a wave of rockets hit a military complex inside an airport in Arbil, killing an Iraqi civilian and a foreign contractor working with the US-led troops.
The attack is claimed by a shadowy pro-Iranian group calling itself Awliyaa al-Dam (Guardians of Blood).
There is no immediate claim of responsibility for Wednesday’s drone attack, but the same group hails the blast in pro-Tehran channels on the messaging app Telegram.