Iraqi Prime Minister Mustafa Al Kadhimi on Saturday announced the arrest of a "terrorist cell" behind a Baghdad market bombing that killed dozens of people and was claimed by ISIS.
The attack renewed fears about the reach of the extremist group, which lost its last territory in Iraq after a military campaign that ended in 2017, but retains sleeper cells in remote desert and mountain areas.
The bombing took place on Monday at Al Woheilat market in Sadr City, a Shiite suburb in the capital, and killed 30 people, excluding the bomber.
"We have arrested all the members of the cowardly terrorist cell that planned and perpetrated the attack," Mr Al Kadhimi said in a post on Twitter, "and they will be put before a judge today."
The prime minister did not say how many people were arrested, but a source at the Interior Ministry said the suspects were expected to make televised "confessions", a common practice for major crimes in Iraq.
Deadly attacks were common in Baghdad during the sectarian bloodletting that followed the US-led invasion of 2003, and later on as ISIS swept across much of Iraq in a rapid 2014 offensive.
Iraq declared ISIS defeated in 2017 after a three-year campaign, and attacks became relatively rare in the capital until January, when ISIS claimed a twin suicide bombing that killed 32 people in another market.
The US-led coalition that supported Iraq's campaign against ISIS has significantly reduced its troop levels over the past year. The capabilities of Iraqi forces had increased substantially, the coalition said.
But US troops have been targeted by powerful pro-Iran Iraqi armed factions which want them to withdraw from the country entirely.
The US and Iran share enmity towards ISIS, but Tehran regards Washington as its arch-nemesis.
An armed drone struck at a military base in Iraqi Kurdistan that hosts American troops, without causing casualties, the coalition said on Saturday.
It was the latest in a spate of attacks on US military and diplomatic facilities in Iraq.
Iraqi Kurdish media outlets said the attack was on a base at Al Harir, 70 kilometres north-east of Erbil, the capital of the autonomous Kurdistan region.
US interests in Iraq have been hit by 50 rocket and drone attacks this year – assaults Washington blames on Tehran-backed factions operating within Iraq's Hashed Al Shaabi paramilitary alliance.
A group calling itself the Iraqi Resistance Co-ordination Committee on Friday threatened to continue the attacks unless the US withdrew all its forces and ended what it called the "occupation".
Most of the US troops deployed in the coalition were withdrawn under US president Donald Trump's administration.
Those who remain are officially classed as advisers and trainers for Iraq's army and counter-terrorism units.
Mr Al Kadhimi is scheduled to meet US President Joe Biden in Washington on Monday to discuss a possible full US troop withdrawal from Iraq.
Analysts said events in the wake of the 2011 US withdrawal from Iraq – notably the rise of ISIS – may make Mr Biden reluctant to authorise a full pullout, for fear of giving the extremists room to regenerate.