Last night in Florida, Secretary of State Hillary Clinton said U.S. specialists hacked into websites run by Al Qaeda’s affiliate in Yemen. The hackers were able to change online ads that boasted about killing Americans into advertisements that underscored the deaths of Muslim civilians in Al Qaeda terror attacks. We're joined by Jamie Doran, a producer for Frontline who worked on the new documentary "Al Qaeda in Yemen."

At least 96 people were killed in the capital city of Yemen yesterday, after a suicide bomber disguised as a Yemeni soldier blew himself up during a military parade rehearsal near the presidential palace in Sana. The bombing was the country's most devastating terrorism attack in years, and the Al Qaeda affiliate that operates within the state has claimed responsibility for the mass killings. Yemen expert Charles Schmitz discusses the country's future.

There’s a new twist in the developing story of a thwarted terrorist plot orchestrated by Al Qaeda in Yemen. The would-be suicide bomber tasked with blowing up a United States-bound airliner was actually a double agent. Scott Shane, national security correspondent for The New York Times, explains.

Tomorrow will mark the one-year anniversary of the Navy SEAL raid on Osama bin Laden's complex in Abbottabad, Pakistan. In the immediate aftermath of the al Qaeda leader's death, many wondered how the organization would be affected. Gideon Rose, the editor of Foreign Affairs, illustrates how the group has changed.

One week ago, Mohammed Merah, a 23-year-old Frenchman of Algerian descent, was shot dead by French security forces following a dramatic 32-hour police standoff. Questions remain about the attack itself: Did Merah act alone? And why didn’t French officials catch him before the rampage? Takeaway producer Arwa Gunja has been in France this week as a reporting fellow with the International Center for Journalists, and spoke with community members about their reaction to both the attacks and the tragedy’s fallout.

New details have come to light about the nine years Osama bin Laden spent on the run in Pakistan after 9/11. We now know he moved among five safe houses and fathered four children, at least two of whom were born in a government hospital. The information has come from a police report by the Dawn newspaper. Mubashir Zaidi is the head of Dawn TV, the Islamabad studio of our partner the BBC.

On March 1, 2003, Khalid Sheikh Mohammad was arrested in Rawalpindi, Pakistan, by members of Pakistan's Inter-Services Intelligence agency and the CIA. It marked the end of one of the lengthiest terrorist manhunts in history. Josh Meyer, chief terrorism reporter for the Los Angeles Times, co-wrote "The Hunt for KSM: Inside the Pursuit and Takedown of the Real 9/11 Mastermind, Khalid Sheikh Mohammad" with Terry McDermott. He discusses the pursuit, detainment, and trial of the man he calls "the ghost of our times."

Mohammed Merah, a French national of Algerian descent and former member of Al Qaeda, was allegedly behind two separate attacks in France this week. Benjamin Abtan, head of the European Grassroots Antiracist Movement, says there is concern that increasing anti-immigration sentiment may have fueled these attacks and that it could lead to others.

Attorney General Eric Holder outlined the United States’ legal defense of using lethal force against U.S. citizens overseas if that citizen is posing a terrorist threat. Holder’s speech, delivered Monday afternoon at Northwestern University, argued in part that the U.S. Constitution’s definition of due process defends the use of lethal force, even without the written consent of the president.

Until now, no legal defense was given for the U.S. mission in Yemen which killed al-Qaeda’s leading figure Anwar al-Awlaki. Al-Awlaki, who was born in the US, was the radical cleric who successfully took al-Qaeda’s message to YouTube.

Despite China and Russia's staunch opposition, the Arab League will return to the United Nations Monday morning to propose a peacekeeping mission in Syria. But the Arab League isn’t the only organization calling for Assad’s ouster: number of jihadi leaders are also offering support to the Syrian opposition, including Al Qaeda leader Ayman Al-Zawahri. Al Qaeda in Iraq, also known as the Islamic State of Iraq, also posted a message of encouragement on its website.

There are increasing worries Al Qaeda is using the instability in Yemen to spread its influence. An American military operation assassinated the radical cleric Anwar al-Awlaki last year. One week ago militants took over the town of Radda. Stephen Sackur, with our partner the BBC, sent this report.

U.S. troops were quietly deployed to northern Uganda last Wednesday to help fight the Lord's Resistance Army, a Christian militia responsible for more than 30,000 deaths and countless rapes and kidnappings in Uganda, the Central African Republic, the Democratic Republic of Congo, and southern Sudan over the past ten years. While the troops are combat ready, their official purpose it to advise the Ugandan military. The real U.S. interests in the region are more complex, however. Once the U.S. has established a military presence in the region, it will be well-positioned to take on a enemy that poses more of a direct potential threat to Americans — al-Qaida in Africa.

On Christmas day in 2009, Umar Farouk Abdulmutallab failed to detonate an explosive device he hid in his underwear, while flying aboard Northwest Flight 253 to Detroit, Mich. Abdulmutallab pleaded guilty in court yesterday to all eight charges against him, including conspiracy to commit terrorism, attempted murder on an aircraft, attempted placement of a destructive device, and the attempted use of a weapon of mass destruction.

Leading Al Qaeda figure Anwar al-Awlaki was killed in Yemen, according to government officials in the country. Al-Awlaki is connected with many plots against Americans including the failed Christmas Day bombing of 2009, the foiled Times Square car bombing, and the Fort Hood shootings. The American-born Al Qaeda leader was a target of an American operation for months although it is unclear if American forces were involved in the operation. U.S. officials did not have an immediate comment.

He was perhaps the Obama Admnistration's most wanted terrorist figure. The CIA reportedly was given the green light to assassinate him, his death has been reported in the past at least twice, he some say he is linked in some way to terrorist attacks and attempts going back 10 years. And it appears this morning that the U.S. born Islamic cleric Anwar Al-Awlaki has finally met his end somewhere in the dusty wilderness of Yemen. A defense ministry official in Yemen confirmed his death early this morning.

Law enforcement officials accused a 26-year-old man from a town west of Boston of plotting to blow up the Pentagon and the Capitol Building with a remote-controlled aircraft fitted with explosives. Officials said Rezwan Ferdaus, who has a physics degree from Northeastern University, has also provided resources to Al Qaida to aid in attacks on American soldiers overseas.

We're talking about the tenth anniversary of 9/11 all this week. And while we’re remembering those we’ve lost, we’re also analyzing the tragedy's aftermath. A new Frontline documentary and investigative book chronicle the proliferation of covert operations and government organizations that began cropping up in the wake of 9/11. Funding for counter-terrorism programs grew exponentially after 9/11. In the documentary, then-White House counter terrorism czar Richard Clarke remembers: "President Bush said to us, in the basement of the White House on the night of 9/11, you have everything you need. And that was true, because as soon as we went to the Congress, they said 'just tell us what you need.' Blank check."

American and Pakistani officials are reporting that a CIA drone strike killed Al Qaeda’s number two man, Atiyah Abd al-Rahman, on Saturday. If the news is true, this could be yet another blow to the organization's high command, following the death of Osama bin Laden in May. But a senior Pakistani security official in the region told Agence France yesterday that he doubts the reports are true, and others have been unable to confirm whether Rahman has in fact been killed.

In their new book, "Counterstrike: The Untold Story of America's Secret Campaign Against al-Qaeda," New York Times reporters Eric Schmitt and Thom Shanker provide an inside look at what goes on behind the scenes of U.S. counter-intelligence, and how national security efforts against terrorism have evolved in the almost ten years since 9/11.

Somali officials confirmed Saturday that they shot and killed Fazul Abdullah Mohammed, the head of al-Qaida in East Africa, and one of the FBI's most wanted terrorists, at a checkpoint on Tuesday. Mohammed had a $5 million bounty on his head for his connections to bombings of embassies in Africa that lead to the deaths of more than 200 people. Secretary of State Hillary Clinton called the killing a "significant blow to al-Qaida."