Washington (CNN) The al Qaeda bomb master behind a 2009 attempt to blow up an airliner over Detroit on Christmas Day may have been killed, according to a UN team that tracks terrorist groups.

The UN report says that Ibrahim al-Asiri, long regarded as one of the most dangerous terrorist operatives in circulation, may have been killed in Yemen last year.

"Since mid-2017, the organization has suffered losses of leadership and field commanders owing to extensive Yemeni and international counter-terrorist operations," said a June report by the Analytical Support and Sanctions Monitoring Team. "Some Member States report that explosives expert Ibrahim al-Asiri ... may have been killed during the second half of 2017. Given al-Asiri's past role in plots against aviation , this would represent a serious blow to operational capability."

The UN report gave no indication of how al-Asiri died or who may have been responsible and is the only public indication of his possible death. But multiple US officials in different parts of the government tell CNN they are weighing evidence that al-Asiri is dead.

The US military and CIA, in addition to Saudi Arabia and United Arab Emirates, have conducted counterterrorism strikes to root out al Qaeda and other terrorists in Yemen. None of these countries have publicly declared that they struck the bombmaker.

The US military carried out 131 airstrikes in Yemen in 2017 and have conducted 34 strikes so far this year, nearly all of them targeting al-Asiri's group al Qaeda in the Arabian Peninsula. The CIA has not revealed how many strikes it has carried out: CIA drone strikes are not publicly acknowledged. The CIA and US military declined comment.

Counter-terrorism analysts say that there should be significant skepticism over al-Asiri's possible demise for one major reason: AQAP has not released any statement acknowledging his death, nor a eulogy celebrating his martyrdom.

Aimen Dean, a former spy for British intelligence inside al Qaeda, told CNN that until such a eulogy is released, al-Asiri should be assumed to be alive.

"It would be extremely out of the ordinary for them not do this for a senior leader like al-Asiri, especially because his group in Yemen are putting out all sorts of statements all the time," Dean told CNN. "Every time a senior leader within al-Qaeda or its affiliate in Yemen has been killed, they have been quick to put out a statement. It's seen as a religious necessity from a Shariah point of view," Dean said, referring to Islamic religious law. "The family of the operative in question must be informed so they can mourn," he said.

The Saudi Arabian native was the mastermind behind the "underwear bomb" attempt to detonate a flight above the skies of Detroit on Christmas day in 2009.

It was one of several plots that made AQAP one of the terror group's most enduring and dangerous affiliates. The Yemeni group has long retained the goal of attacking the US directly and al-Asiri, who led their bomb making efforts for years, played a significant role in trying to make that happen.

Al-Asiri is widely credited with perfecting miniaturized bombs with little or no metal content that could make it past some airport security screening. That made him a direct threat to the United States and he has come close to wreaking devastation on US targets in the past.

The son of a Saudi military officer, al-Asiri allegedly designed the so-called "underwear bomb" worn by Umar Farouk Abdulmutallab, a Nigerian who tried to blow up an airliner as it was landing in Detroit on Christmas Day 2009.

Al-Asiri masterminded other plots as well, including an assassination attempt earlier that year. In that August 2009 scheme, al-Asiri created a small bomb contained 100 grams of a powdery explosive that his younger brother Abdullah concealed inside his rectum in a failed attempt to assassinate Saudi Arabia's counterterrorism chief Prince Muhammad bin Nayef.

Synagogues in Chicago

Abdullah died in the blast.

Al-Asiri was also behind the so-called "printer bomb" plot, in which US-bound explosive devices were found inside printers being shipped through Dubai and the UK in October 2010.

The packages were shipped from Yemen. Both were addressed to synagogues in Chicago.

Al-Asiri appears to have taken on a more public-facing role within AQAP in recent years, including purportedly recording an audio speech that was released by the group in 2016.

The most recent public statement attributed to him was a written speech released by AQAP on September 12, 2017, to coincide with the sixteenth anniversary of the terrorist attacks of 9/11. Al-Asiri used the occasion to promise an ongoing war against the United States.

CNN cannot independently verify he was truly the author of these statements.

If al-Asiri is dead, few expect his expertise to die with him. Security officials believe he has trained a number of apprentices in advanced bomb making. And since 2014, US officials have been concerned that the bomb-making expertise built up by AQAP has migrated to other groups, including al Qaeda operatives in Syria.

Meanwhile, as CNN reported in 2017, ISIS is among the terrorist groups that have worked to develop laptop bombs, prompting large electronics to be temporarily banned in the cabin on certain flights to the United States and the UK from the Middle East last year.