WASHINGTON, United States (AFP) — An Islamic State (IS) operative who allegedly planned the 2021 suicide bombing outside Kabul airport during the chaotic US military withdrawal has been arrested, President Donald Trump said Tuesday.

The bomber detonated a device among packed crowds as they tried to flee Afghanistan, killing 170 Afghans and 13 American troops securing the perimeter, days after the Taliban seized control of the capital.

On Tuesday, in his first address to Congress since returning to the White House for a second term, Trump announced that Pakistan had assisted in the arrest of “the top terrorist responsible for that atrocity.”

“And he is right now on his way here to face the swift sword of American justice,” he said, taking a swipe at his predecessor Joe Biden’s oversight of the “disastrous and incompetent withdrawal from Afghanistan.”

He thanked Pakistan “for helping arrest this monster” but gave no details of the suspect or the arrest operation.

The US withdrew its last troops from Afghanistan on 31 August 2021, ending a chaotic evacuation of tens of thousands of Afghans who had rushed to Kabul’s airport in the hope of boarding a flight out of the country.

Images of crowds storming the airport, climbing atop aircraft — and some clinging to a departing US military cargo plane as it rolled down the runway — aired on news bulletins around the world.

Pakistani sources identified the suspect as Mohammad Sharifullah, also known as Jafar, a leader of the IS branch in Afghanistan and Pakistan.

US news platform Axios, citing two unidentified US officials, said Sharifullah was in the process of being extradited from Pakistan to the United States and was expected to arrive on Wednesday.

In April 2023, the White House announced that an IS official involved in plotting the attack at the airport’s Abbey Gate had been killed in an operation by Afghanistan’s new Taliban government.

Pakistan’s Prime Minister Shehbaz Sharif thanked Trump for “acknowledging and appreciating Pakistan’s role and support” in counter-terrorism efforts in Afghanistan.

“We will continue to partner closely with the United States in securing regional peace and stability,” he wrote on social media platform X.

Pakistan’s strategic importance has waned since the US and NATO withdrawal from Afghanistan, but militancy has rebounded in the border regions.

Islamabad accused Kabul of failing to root out militants sheltering on Afghan soil, a charge the Taliban government denies.

The regional chapter of the IS group, known as the IS Khorasan, has staged a growing number of bloody international attacks, including killing more than 140 at a Moscow concert hall and more than 90 in an Iranian bombing last year.