Al Qaeda Leader Vows Revenge So Fierce That U.S. Will Miss Osama Bin Laden

VIDEO: U.S. officials say Pakistan will allow his three wives to be
WATCH Osama Bin Laden's Widows to Come Forward

A leader of the al Qaeda offshoot that U.S. officials have called the greatest threat to the U.S. vowed in a message posted on Islamist websites Wednesday to take revenge against the U.S. for the death of Osama bin Laden, saying that jihad would only intensify and that Americans would come to "wish for the days of Osama."

"Do not dismiss this battle so easily, and give your people false hope that if you kill Osama that it is over," promised Nasir al-Wahishi, a leader of the Yemen-based al Qaeda in the Arabian Peninsula (AQAP). "What is waiting for you is far greater and more dangerous, and you will then count your regrets, wishing for the days of Osama."

Wahishi said the U.S. made a "big mistake" by killing bin Laden. "For those who celebrated the killing of our sheikh," says the statement, "we tell them: We will see if you celebrate what the sons and students of the sheikh will send you."

Follow ABCNewsBlotter on Twitter

A threat against the U.S. was also leveled by U.S.-born Omar Hammami, also known as Abu Mansur al-Amriki or The American, who speaks for the Somali branch of al Qaeda, Al Shabaab.

"We are sending a message to [U.S. President Barack] Obama and [Secretary of State] Hillary Clinton that we will avenge the death of our leader Sheikh Osama bin Laden very soon," Hamami said during a Shabaab meeting in Afgoye town west of the capital Mogadishu, according to a report by the Agence France Presse. Hammami did not say when or how Al Shabaab planned to act.

Hammami, who was raised in Alabama, was believed to have been killed this spring in fighting in Somalia, but then released the latest of several pro-jihadi rap songs.

READ: Alabama-Born Al Qaeda Spokesman, Reported Dead, Releases More Hip Hop Tracks

Officials: Al Qaeda in Yemen 'Most Significant Risk' to U.S.

Earlier this year, National Counterterrorism Center director Michael Leiter called AQAP "the most significant risk to the U.S. homeland." In March, Defense Secretary Robert Gates said AQAP was al Qaeda's most dangerous branch.

AQAP has claimed responsibility for the failed "underwear" bombing of Northwest flight 253 on Christmas Day 2009, and last November's parcel bomb plot, in which bombs were shipped via FedEx and UPS from Yemen to targets in the U.S. The bombs were intercepted before they could detonate.

Just four days after bin Laden was killed in by Navy SEALs in a raid on his Pakistan compound, the U.S. attempted to kill AQAP leader Anwar al-Awlaki with a drone attack in southern Yemen. While several AQAP members were reportedly killed, Awlaki survived the missile attack.

President Obama has authorized the CIA and the military to kill Awlaki, a U.S.-born radical cleric linked to accused Fort Hood shooter Maj. Nidal Hasan and alleged underwear bomber Umar Farouk Abdulmutallab. Officials of the Yemeni government, which has been fighting AQAP with U.S. aid, said in September that soldiers had surrounded Awlaki in the village of Houta, but then said soldiers had instead captured two-dozen al Qaeda fighters and a "vital terror headquarters."

In his statement, AQAP leader Wahishi also threatened Arab leaders who are cooperating with the U.S. in the hunt for al Qaeda. He pledged "intensive and harmful revenge" on the U.S and any "allies who celebrated the death of bin Laden, including the Yemeni and Saudi governments."

Follow ABCNewsBlotter on Facebook

Click Here for the Blotter Homepage.