The recent terrorist attacks in Kampala, Uganda, and the court hearing Monday of an American charged with trying to join the jihad in Somalia, are worrisome signs that a new transnational terrorist network is taking shape in East Africa--one that may have its sights set on the United States. That's the bad news. The worse news is that President Obama ordered the killing of the man who could have helped us to disrupt and destroy this network.

Responsibility for the blasts in Kampala has been claimed by al-Shabab. The State Department designated the group in March 2008 as a foreign terrorist organization, noting that al-Shabab included "individuals affiliated with al-Qa'ida" and citing its efforts to "undermine the Somali government" and "destabilize the Horn of Africa region." But the truth about al-Shabab is far more sinister. In the summer of 2008, the group merged with al-Qaeda. Last year, al-Shabab released a video showing its fighters chanting "Here we are O' Osama. We are your soldiers O' Osama," while the group's leader, Abu Zubair, promised bin Laden that "Allah willing, the brigades for Global Jihad will be launched from [Somalia] to deprive the disbelievers of sleep and destroy their interests around the world."

With the Uganda bombings, the group seems to have made good on this promise, carrying out its first large-scale attack outside Somalia. Where else have they set their sights? One clue: al-Shabab is actively recruiting Americans. On Monday, a 20-year-old Northern Virginia man, Zachary Adam Chesser, will appear in federal court on charges of attempting to travel to Somalia to join al-Shabab as a foreign fighter. Before his planned departure, Chesser had been in direct communication with Anwar al-Aulaqi, the cleric in Yemen who reportedly helped to guide the men behind the attempted Christmas Day bombing over Detroit and who also had been in contact with the Fort Hood shooter.

Chesser is not the first American to try to join al-Shabab. In June, two New Jersey men were similarly arrested at New York's John F. Kennedy International Airport for allegedly planning to fight with the terrorist group. And about 20 young Somali Americans have reportedly left Minnesota over the past few years to join the group. Not only is the group recruiting American fighters, one of the group's leaders is an American citizen; Omar Hammami, who grew up in Alabama, has justified the Sept. 11, 2001, attacks and affirmed his group's allegiance to bin Laden.

The fact that al-Qaeda's new East African affiliate is seeking out Americans is an ominous sign. After all, you don't need fighters with U.S. passports if your only intent is to conduct operations in Africa. We overlook these warnings at our peril. The United States failed to anticipate the Christmas Day attack because, as a May 2010 Senate Intelligence Committee report put it, "Intelligence analysts were primarily focused on Al-Qaeda in the Arabian Peninsula (AQAP) threats to U.S. interests in Yemen, rather than on potential AQAP threats to the U.S. homeland." We must not repeat this mistake with al-Qaeda in East Africa.

The best way to uncover the terrorists' intent and capabilities would be to capture and interrogate their top leaders. The Obama administration had the chance to do just that last September, when the United States tracked down Saleh Ali Nabhan, al-Qaeda's leader in East Africa and also a senior leader in al-Shabab, who was responsible for the merger of the two groups. The Post reported that Obama was given three options for Nabhan's disposition: U.S. Special Operations forces could kill him with an airstrike while he was driving through southern Somalia. They could kill him by firing from helicopters, then land and confirm the kill. Or they could try to take him alive. At least some in the military wanted him alive. "We wanted to take a prisoner," a senior military officer said. But the Obama administration chose the second option--Nabhan was killed by helicopter and his body recovered by Special Operations commandos. As a result, The Post reported, "the opportunity to interrogate one of the most wanted U.S. terrorism targets was gone forever."

Nabhan might have provided the United States with invaluable intelligence--information available nowhere else about his terror network, its American recruits and its plans for new attacks. But thanks to a decision by Obama, all that intelligence was vaporized. Why did the president choose to kill, rather than capture, Nabhan? U.S. officials told The Post it was in part because of "the memory of the last time a U.S. combat helicopter was on the ground in lawless Somalia, the 1993 Black Hawk debacle that resulted in the deaths of 18 soldiers."

Since Nabhan's death, al-Shabab's Saleh Ali Nabhan Brigade (named for the deceased leader) carried out its attacks in Kampala that resulted in the deaths of at least 74 people, including an American aid worker, and critically injured a 16-year-old Maryland girl.

The next attack could be even more deadly--and could come much closer to home.

Marc A. Thiessen is a visiting fellow at AEI.

Photo credit: Trymore MacVivo