Al-Qaida in the Arabian Peninsula is the top security threat to the United States and the bomb maker thought to have created at least two non-metallic explosive devices must be killed to safeguard national security, a top senator said on Sunday.
"I am hopeful that we will be able to, candidly, kill this bomb maker and kill some of these other associates, because there is a dangerous process in play at the present time," Sen. Dianne Feinstein, chairwoman of the Senate Select Committee on Intelligence, told "Fox News Sunday."
The bombs, intended to be smuggled aboard an aircraft undetected and then detonated, bear the forensic signature of suspected al-Qaida bomb maker Ibrahim Hassan al-Asiri, who is believed to be hiding in Yemen, officials have said.
They said a bomb obtained in a recent intelligence operation appeared to be an upgraded version of the so-called "underwear bomb" that failed to bring down a passenger jet over Detroit on Christmas Day 2009.
A bomber from the al-Qaida affiliate in Yemen sent to blow up a U.S.-bound airliner last month was actually a double agent who infiltrated the group and volunteered for the suicide mission, intelligence agency officials have confirmed.
Saudi Arabia's intelligence agency, working with British intelligence and the CIA, placed the operative inside al-Qaida in the Arabian Peninsula, or AQAP, with the goal of convincing his handlers to give him a new type of non-metallic bomb for the mission, officials said.
Western intelligence agencies have identified AQAP as among the most dangerous and determined al-Qaida affiliates in the world, dedicated in part to attacks on the West.
The double agent arranged instead to deliver the device to U.S. and other intelligence authorities waiting outside Yemen, the officials said.
The main charge was a high-grade military explosive that "undoubtedly would have brought down an aircraft," the New York Times reported, citing a senior U.S. official.
Feinstein said a leak early last week on the operation to the Associated Press "is very serious."
"The leak did endanger sources and methods, and the leak I think has to be prosecuted."
" ... It gives a tip off to AQAP to be more careful about who they use as their couriers, as their bombers. ... Criminal charges will go to the Department of Justice."
Rep. Peter King, chairman of the House of Representatives Homeland Security Committee, told CNN's "State of the Union" the premature leak of the operation to the AP was criminal and damaging.
"The FBI has to do a full and complete investigation because this really is criminal in the literal sense of the word to leak out this type of sensitive, classified information on really almost unparalleled penetration of the enemy," King said.
"This was more secret than any operation I'm familiar with, even more secret than (the assassination of Osama) bin Laden." Yet "the Associated Press apparently had the entire story."
The leak put lives at risk and the operation had to be cut short, King said. "It sends a signal to countries willing to work with us that we can't be trusted to keep a secret if in fact we are the ones who leaked it out."
"I think there was a bit of premature chest-thumping in this whole thing," Representative Mike Rogers, chairman of the House Intelligence Committee, told CBS's "Face the Nation."
"No national security operation ever should be used for a headline under any circumstances," suggesting someone with ties to the intelligence community had sought political gain from the operation.
Feinstein was asked if current screening technology would necessarily identify this kind of bomb on an airline passenger. "For this particular material," she said, "candidly, no."
"I think Americans have to understand that this particular kind of explosive, non-metallic, is not easily detectable."
Consequently the flying public is going to have to tolerate more invasive searches, she said. "The American public has not been terribly sympathetic" to this, she said, but "it's very important that TSA (the Transportation Security Administration) keeps up its efforts."
Meanwhile, a senior aide to President Barack Obama flew into Yemen on Sunday to meet the leader of a country battling with al-Qaida insurgents, a Yemeni official said.
The visit of John Brennan, the U.S. president's counter-terrorism adviser, comes as Yemen is on a new offensive against Islamist rebels.
Washington has stepped up its drone attacks in Yemen since President Abd-Rabbu Mansour Hadi took office in February, and the Pentagon said this week it had recently resumed sending military trainers into the Gulf Arab country.
In a brief statement, the U.S. embassy in Yemen said Brennan had "conveyed President Obama's strong commitment to support Yemen as it continues to implement its political agreement and prepares for a comprehensive national dialogue."
No other details of the meeting were immediately available.
Mohammed al-Basha, a Washington-based Yemeni government spokesman, said earlier that Brennan had flown into Yemen `"to reiterate holistic U.S. support to Yemen not only in the field of counter-terrorism but also by providing assistance to help Yemen overcome its many other economic and security challenges."
Washington backed a power transfer plan that made Hadi the successor to President Ali Abdullah Saleh after a year of mass protests which coincided with a split in the army that threatened to erupt into civil war.
The deal stipulates the new president should lead Yemen through a two-year period in the hope that the impoverished nation will be able to use that time to end political chaos.
Brennan's visit comes amid increasing attacks on officials and foreign diplomats as Yemen tries to wrest back control of its restive south from Islamist rebels.
Unidentified assailants hurled a hand grenade at the house of Information Minister Ali al-Amrani on Saturday. A bystander was wounded in the foot during a shoot-out as the men escaped, Abdel-Basset al-Qaedi, a member of Amrani's staff, said.
In January, gunmen opened fire on the information minister's car in an apparent assassination attempt, and on Saturday Bulgaria's ambassador escaped an apparent kidnap attempt in the capital Sanaa.
On Sunday, at least 10 militants were killed in clashes with the Yemeni army near the southern city of Zinjibar. Six militants were killed on Saturday night in an air strike in Zinjibar, the Defence Ministry said in an online statement.
Two apparent U.S. drone attacks killed at least 10 suspected al-Qaida-linked militants on Saturday, officials said.
Yemen's interior ministry said on Sunday two of the militants killed in the air strikes were Saudi.
The United States and Saudi Arabia, both targets of failed attacks by Yemen's al-Qaida branch, want Hadi to unite the army and roll back gains made by Islamists who seized southern towns during the political turmoil.