The man whom U.S. Navy SEALs tried to seize in Somalia this past weekend is a senior operative of al-Shabab who has tried to expand the reach of the al-Qaeda-linked militia into Kenya, a critical U.S. ally in East Africa, according to analysts and officials.

The attempt to capture Abdulkadir Mohamed Abdulkadir, also known as Ikrima, failed. Arriving in speedboats, the U.S. commandos engaged in a fierce gun battle with al-Shabab militants in the oceanside town of Barawe before retreating. Ikrima is believed to have survived the assault on his villa.

Ikrima is suspected of being an operations planner and recruiter for al-Shabab as well as a key figure in al-Hijra, a shadowy Kenyan group that has become al-Shabab’s wing inside Somalia’s East African neighbor.

A Kenyan citizen of Somali descent, Ikrima routinely travels between Kenya and Somalia, according to analysts. He has planned or carried out major attacks in both countries since 2011, according to Kenyan intelligence officials, U.N. security experts and regional analysts.

The growing threat posed by Islamist Kenyan militants is underscored by the role they played in the siege of a Nairobi shopping mall on Sept. 27, which left more than 60 people dead. Al-Shabab claimed responsibility for the attack. But Kenyan authorities say at least one of the five attackers killed was a Kenyan, as is a key suspect in the plot who is still alive. At least two of the dead assailants were believed to be members of al-Hijra, according to Matt Bryden, the former head of the U.N. Monitoring Group on Somalia and Eritrea.

It’s unclear whether Ikrima was connected to the mall attack, but analysts said it is plausible that he was one of the planners.

‘Blowback’ in East Africa

Al-Hijra’s rising profile is the latest sign of growing Islamic radicalization in East Africa, which had been considered one of the continent’s most stable regions. The group, mainly comprising ethnic Somalis and radical members of Kenya’s Muslim minority, was once known for small grenade attacks and drive-by shootings. But as the insurgency flared in Somalia in the past seven years, Kenyan and other East African extremists saw an opportunity to gain military training and fight a jihad — and then return home to use their skills.

“Partly what we are seeing now is blowback,” said Bryden, who heads Sahan Research, a Nairobi-based think tank. “The people who spent time in Somalia are now coming back to use that experience in their country.”

There was a clear symbiosis between the groups in the two countries, he said.

“Ikrima represents an interesting crossover between al-Hijra and al-Shabab, as a Kenyan who can mingle among both the Somalis and the foreign fighters,” he said.

Last year, Ikrima topped a “most wanted” list of six people named by Kenyan authorities as militants suspected of recruiting Kenyans into al-Shabab. Some analysts ascribe even more importance to Ikrima. “Within al-Shabab, Ikrima was reportedly put in charge of Kenyan fighters, both ethnic Somali and non-ethnic Somali,” said J. Peter Pham, head of the Africa Center at the Atlantic Council.

A Kenyan intelligence report provided to The Washington Post and other media outlets details several instances in which Ikrima attempted to carry out devastating attacks in Nairobi.

In December 2011, two months after Kenya dispatched its troops into Somalia to fight al-Shabab, Ikrima “envisioned multiple attacks” that were “sanctioned by Al Qaeda core in Pakistan,” the report read. They included “targeting Parliament buildings, the U.N. office in Nairobi” as well as Kenyan military camps and an Ethiopian restaurant frequented by members of Somalia’s Western-backed transitional government. Ikrima was also planning to assassinate top Kenyan political and security officials and to disrupt Kenya’s presidential elections held earlier this year, the report read.

“By December 2011, the planners had acquired safe houses in Nairobi and Mombasa, trained the executors, received explosives from Somalia and commenced assembly of and concealment of explosives,” the report read.

But none of the attacks described in the intelligence report were carried out. Kenyan authorities said they had foiled them.

The planned attacks, the report said, involved operatives trained by Fazul Abdullah Mohammed and Saleh Ali Saleh Nabhan, two of al-Qaeda’s most senior operatives in East Africa, who analysts said were mentors to Ikrima. The two al-Qaeda figures were suspected of masterminding the twin 1998 bombings of the U.S. embassies in Nairobi and in Dar es Salaam, Tanzania, and the 2002 attacks on an Israeli-owned hotel and airliners in Mombasa, Kenya.

Warnings about Ikrima

The strike against Ikrima was the most significant U.S. operation inside Somalia since September 2009, when Nabhan was slain in a U.S. Special Operations mission.

Ikrima has also been implicated in plots inside Somalia. In May of this year, a U.N. security analyst got a tip that Ikrima and members of al-Shabab’s intelligence wing, known as al-Amniyat, were planning to attack the U.N. humanitarian compound in the capital, Mogadishu, as well as several Somali government and Western targets, according to a confidential e-mail by the analyst obtained by The Post.

“The threat information is without doubt the most specific that we . . . have received in the past two and a half years,” the e-mail said.

The United Nations received a second warning on June 1, indicating that Ikrima had urged al-Shabab to proceed with the attack on the U.N. compound and to also target the city’s airport, which housed African Union peacekeepers and the political headquarters of the U.N. special representative, Nicholas Kay.

The group never struck the airport, but on June 19, an al-Shabab militant set off a car bomb outside the entrance of the U.N. compound, allowing six militants to rush inside, where they killed four Somali guards, three U.N. contractors and a U.N. humanitarian aid worker. All of the al-Shabab attackers were killed.

Al-Shabab leaders have described the foiled U.S. raid this weekend as a victory for their side.

A U.S. military official, speaking on the condition of anonymity to discuss a sensitive mission, said that the goal of the operation was to capture Ikrima alive but that the Navy SEAL team withdrew after encountering heavy fire and concluding that it would be too difficult to take him alive. The team was also concerned about the risk of inflicting casualties on innocent bystanders.

“It was a capture mission, and when it became evident that we couldn’t capture him alive, the team decided” to withdraw, the official said. “If we wanted to kill this guy, we have lots of ways to do that.”

Pentagon spokesman George Little said via Twitter on Monday: “Seeing some suggestions that one of our military ops wasn’t successful. We knocked on al-Shabaab’s front door. They shouldn’t sleep easy.”

According to the Kenyan intelligence report, Ikrima sometimes worked with South African operatives to bring grenades, guns and explosives into Kenya. In the plot approved by al-Qaeda central in Pakistan, Ikrima allegedly worked with two British jihadists, Jermaine Grant and Samantha Lewthwaite, whom the British media has dubbed the “White Widow.”

Grant is on trial in Mombasa, accused of possessing bombmaking materials. Lewthwaite, the widow of one of the suicide bombers who targeted the London transit system in 2005, is wanted by Interpol and Kenyan authorities.

Lynch reported from the United Nations. Craig Whitlock in Washington contributed to this report.