Intelligence analysts paid close attention last month when al Qaeda's master bombmaker, Ibrahim al Asiri — whose name tops U.S. kill lists — issued an audiotape from his hiding place.
The content was the usual anti-Saudi Arabian screed, sprinkled with threats against America — but the news was Asiri's sudden willingness to join the terror group's PR campaign. For years, the man who tried to take down planes with underwear and parcel bombs had laid low, as al Qaeda's Yemen affiliate tried to protect him from U.S. drone strikes.
In 2016, however, a resurgent al Qaeda is emerging from the shadows. While ISIS has been soaking up headlines, its older sibling has been launching attacks and grabbing territory too, and U.S. intelligence officials tell NBC News they are increasingly concerned the older terror group is poised to build on its achievements.
"Al Qaeda affiliates are positioned to make gains in 2016," James Clapper, the director of national intelligence, warned the House Intelligence Committee Thursday.
Because of those far-flung affiliates, al Qaeda "remains a serious threat to U.S. interests worldwide," Lt. Gen. Vincent Stewart, the director of the Defense Intelligence Agency, told Congress recently.
After seizing a large segment of Iraq and Syria, beheading Western hostages on camera and slaughtering civilians in the heart of Paris, ISIS has eclipsed its extremist rival as the biggest brand in global jihad.
But U.S. officials tell NBC News that al Qaeda — though its core in Pakistan has been degraded by years of CIA drone strikes — is now experiencing renewed strength through its affiliates, led by al Qaeda in the Arabian Peninsula (AQAP) in Yemen and the Nusra Front in Syria. Clapper called the two groups al Qaeda's "most capable" affiliates in his House testimony Thursday.
Both branches have expanded their territorial holdings over the last year amid civil wars. Russian air strikes against the Nusra Front, and CIA drone attacks on AQAP leaders, have set them back, but have not come close to destroying them.
Al Qaeda has not managed to attack a Western target recently, but it continues to inspire plots. There is no evidence December's mass shooting in San Bernardino, California was directed by al Qaeda, but Syed Rizwan Farook, who carried out the attack with his wife Tashfeen Malik, appears to have been radicalized by al Qaeda long before the rise of ISIS. He was a consumer of videos by al Qaeda's Somalia affiliate and the AQAP preacher Anwar al Awlaki, court records show.
Al Qaeda attacks on hotels in Burkina Faso in January and Mali in November, which together killed dozens of people, appeared to affirm the threat posed by the terror group's Saharan branch, al Qaeda in the Islamic Magreb, or AQIM.
Stewart added that intelligence officials are also "concerned al Qaeda could reestablish a significant presence in Afghanistan and Pakistan, if regional counterterrorism pressure deceases."
In Yemen, AQAP has benefitted from the power vacuum created by the Houthi rebels' uprising, and the air war on the Houthis by Saudi Arabia.
AQAP last April seized the city of Mukalla, the capital of Hadramout province and a port city with a population of some 300,000. It looted a bank of more than $1 million in cash, U.S. officials said, and released 300 inmates from jail.
Since then, the group has expanded its territory in the provinces of Abyan and Shabwa, its traditional strongholds.
"AQAP's expansion is unchecked because there is no one on the ground to put any pressure on the organization," noted Geoffrey Johnsen, a Yemen expert. "What is left of Yemen's military is too busy fighting other enemies to engage AQAP, and the Saudis are focused on rolling back the Houthis. In the midst of Yemen's civil war, AQAP is able to pursue more territory and to plot, plan, and launch attacks."
The CIA is watching closely. Jalal Bala'idi, a prominent AQAP field commander, was killed in an agency drone strike in February.
AQAP's seizures of territory have "allowed them to operate more openly, have access to a port, and have access to other kinds of infrastructure that has certainly benefitted them," a U.S. intelligence official told NBC News. At the same time, he said, the U.S. has "managed to remove many significant figures from the battlefield and keep AQAP somewhat at bay."
Al Qaida's Syrian affiliate gets less public attention than others. Western media reporting sometimes refers to the Nusra front as a Syrian rebel group, without mentioning that it's part of the global terrorism organization.
But Nusra is as well-organized and disciplined as any al Qaeda affiliate, U.S. intelligence officials say. Although it is now focused on defeating Assad, its battle tested fighters could pose a risk to the West in the years ahead.
"Jabhat al Nusra is a core component of the al Qaeda network and probably poses the most dangerous threat to the U.S. from al Qaeda in the coming years," the Institute for the Study of War, a Washington think tank, said in a recent report. "Al Qaeda is pursuing phased, gradual, and sophisticated strategies that favor letting ISIS attract the attention — and attacks — of the West while it builds the human infrastructure to support and sustain major gains in the future and for the long term."
U.S. air strikes have set back a group of al Qaeda operatives in Syria known as the Khorasan Group, which embedded with Nusra while plotting attacks against the West, intelligence officials say.
But Nusra has trained a core of elite fighters, the ISW says. Georgetown terrorism expert Bruce Hoffman says Nusra has achieved Osama bin Laden's goal of rebranding al Qaeda and moving away from a name that had lost its luster.
The group's leader, Abu Mohammad al Julani, is hardly a household name in the West, but he is respected by his adversaries in American intelligence. He is believed to have been detained by the U.S. military in Iraq and released in 2008.
Hoffman, who served as the CIA's Scholar-in-Residence for Counterterrorism, calls Nusra "even more dangerous and capable than ISIS."
Al Qaeda is watching ISIS "take all the heat and absorb all the blows while al Qaeda quietly re-builds its military strength," he said.