NAIROBI, Kenya -- A Navy SEAL team targeted a senior leader of the Shabab militant group in a raid on his seaside villa in the Somali town of Baraawe on Saturday, American officials said, in response to a deadly attack on a Nairobi shopping mall for which the group had claimed responsibility.
The SEAL team stealthily approached the beachfront house by sea, firing on the unidentified target in a predawn gunbattle that was the most significant raid by American troops on Somali soil since commandos killed Saleh Ali Saleh Nabhan, a Qaeda mastermind, near the same town four years ago.
The Shabab leader was believed to have been killed in the firefight, but the SEALS were forced to withdraw before that could be confirmed, a senior American official said. Such operations by American forces are rare because they carry a high risk, and indicate that the target was considered a high priority. Baraawe, a small port town south of Mogadishu, the Somali capital, is known as a gathering place for the Shabab's foreign fighters.
"The Baraawe raid was planned a week and a half ago," said an American security official, speaking on the condition of anonymity about a classified operation. "It was prompted by the Westgate attack," he added, referring to the mall in Nairobi that was overrun by militants two weeks ago, leaving more than 60 dead.
Witnesses in the area described a firefight lasting over an hour, with helicopters called in for air support. A senior Somali government official who spoke on the condition of anonymity confirmed the raid, saying, "The attack was carried out by the American forces and the Somali government was pre-informed about the attack."
A spokesman for the Shabab, which is based in Somalia, said that one of its fighters had been killed in an exchange of gunfire but that the group had beaten back the assault. American official initially reported that they had seized the Shabab leader, but later backed off of that account. The deadly assault on the Westgate shopping mall was a stark reminder of the power and reach of the Islamist group, which had a series of military setbacks in recent years and was widely viewed as weakened.
The F.B.I. sent dozens of agents to Nairobi after the shopping mall siege to help Kenyan authorities with the investigation. United States officials fear that the Shabab could attempt a similar attack on American soil, perhaps employing several of the group's Somali-American recruits.
Another United States official said it was still unclear whether any Americans were involved in the Westgate mall episode, though there were growing indications that fewer attackers took part in the siege than the 10 to 15 militants the government had previously announced.
A spokesman for the Kenyan military said Saturday that it had identified four of the attackers from surveillance footage. Local news media reported their names as Abu Baara al-Sudani, Omar Nabhan, Khattab al-Kene and a man known only as Umayr. "I can confirm that those are the names of the terrorists," said Maj. Emmanuel Chirchir, the spokesman.
The footage, broadcast on Kenyan television on Friday night, showed four of the attackers moving about the mall with cool nonchalance, no hint in their demeanor that they had stormed a shopping center and massacred dozens of people, much less that they feared an imminent counterassault from Kenyan security services.
One loitered in the grocery checkout aisle, talking on his cellphone. Another slouched in a storage room like a worker on break.
At least one of the four men, Mr. Nabhan, is Kenyan, and believed to be related to Saleh Ali Saleh Nabhan, the Qaeda mastermind killed four years ago near Baraawe.
The elder Mr. Nabhan was a suspect in the bombing of an Israeli hotel on the Kenyan coast in 2002 and the attacks on the American Embassies in Kenya and Tanzania in 1998.
He was one of the most wanted Islamic militants in Africa when American commandos killed him in September 2009 in an audacious daytime attack. Four military helicopters shot at two trucks rumbling through the desert, killing six foreign fighters, including Mr. Nabhan, and three Somali members of the Shabab.
Mr. Nabhan was of Yemeni descent but was born in Mombasa, on Kenya's coast. Kenyan news media reported that the younger Mr. Nabhan also came from Mombasa, and was among the Kenyans who traveled to Somalia to train and fight with the Shabab.
Matt Bryden, the former head of the United Nations Monitoring Group on Somalia and Eritrea, said the tactics used in the Westgate attack were similar to those used by the Shabab in a number of operations in Somalia this year. But he also said that local help was needed to pull off an attack on that scale, and that several of the men identified as taking part in the attack were connected to group's Kenyan affiliate, known as Al Hijra.
"We should certainly expect Al Hijra and Al Shabab to try again," Mr. Bryden said. "And we should expect them to have the capacity to do so."
The raid on Saturday morning appeared to have been intended to blunt those capabilities. A witness in Baraawe said the house was known as a place where senior foreign commanders stayed, though he could not say whether they were there at the time of the attack.
The witness said 12 well-trained Shabab fighters scheduled for a mission abroad were staying there at the time of the assault. He confirmed that a Somali man was killed in the attack.
There was some confusion as to exactly what happened before sunrise on Saturday. Witnesses described the SEAL team using silencers in the initial attack, but a loud firefight afterward. Before confirmation that an American SEAL team was behind the attack, a Shabab spokesman said British and Turkish forces were involved, which both countries immediately denied.
Nicholas Kulish reported from Nairobi, and Eric Schmitt from San Francisco. Reporting was contributed by Josh Kron from Mombasa, Kenya; Sebnem Arsu from Istanbul; Michael S. Schmidt from Washington; and Mohammed Ibrahim from Mogadishu, Somalia.world
This article originally appeared in The New York Times.