US officials are reportedly confident that al-Qaeda in the Arabian Peninsula's suspected chief bomb maker, Ibrahim al-Asiri, has been killed.
US media cited sources as saying they believed the Saudi militant died in a US drone strike in Yemen last year.
Asiri is alleged to have been behind the 2009 underwear bomb plot and made devices found on cargo planes in 2010.
Intelligence suggesting he was working on a bomb hidden in a laptop or tablet led the US to ban them on some flights.
A UN report published last week, which also said Asiri might have been killed, said his death would represent "a serious blow" to AQAP's operational capability.
A Yemeni tribal leader told the Associated Press on Friday that Asiri was killed in a missile strike, along with two or four associates, in Marib province.
AQAP has not commented on the reports or published a eulogy for Asiri, as it has done for other leaders and field commanders killed by the US and its allies.
The US designated Asiri, 36, as a "Specially Designated Global Terrorist" in 2011 and has offered a $5m (£3.9m) reward for any information leading to his capture.
Before joining AQAP, he was part of an al-Qaeda cell in Saudi Arabia and was allegedly involved in planned bombings of oil facilities in the kingdom.
Asiri gained notoriety for the recruitment of his younger brother, Abdullah, as a suicide bomber.
In August 2009, Abdullah detonated a bomb concealed within his body in an attempt to assassinate Saudi Arabia's then security chief, Prince Mohammed Bin Nayef Bin Abdul Aziz Al Saud, who escaped with minor injuries.
The bomb contained the explosive pentaerythritol tetranitrate (PETN), and used a detonator with a chemical fuse, which was not spotted by a metal detector.
After the death of his brother, Asiri is thought to have designed the underpants bomb allegedly used by a young Nigerian man, Umar Farouk Abdulmutallab, in an attempt to blow up a US passenger jet as it flew into Detroit on Christmas Day 2009. That device also contained PETN and had a chemical fuse.
He is also believed to have made PETN bombs hidden in two printer cartridges, which were found on cargo planes in Dubai and the UK in October 2010. The cartridges were inside packages sent from Yemen to the US.
Intelligence reports that Asiri was developing bombs that could be hidden in portable electronic devices led to the US authorities banning uncharged laptops and mobile phones from flights to the US from Europe and the Middle East in 2014.
And in March 2017, reportedly after fresh intelligence about AQAP's activities was obtained in a raid in Yemen, the US banned all laptops and large mobile devices in hand luggage on flights from major airports in the Middle East.