US Secretary of State John Kerry said Monday the capture of an Al-Qaeda operative in Libya was "appropriate and legal" but added that Washington had not informed the Libyan government of the operation.

Kerry told journalists at the Asia-Pacific Economic Cooperation forum on the Indonesian island of Bali that the United States does "everything in its power that is appropriate and legal" to hunt down terrorists.

He also said the United States "does not go into the specifics" with foreign governments about operations such as the one that led to the capture of Abu Anas al-Libi at the weekend.

The United States pledged Sunday to keep "relentless pressure" on terror groups following the daring capture of an Al-Qaeda operative in Libya and the storming of a Shebab stronghold in Somalia.

The tough talk from Washington, however, was met with questions in Tripoli, where officials demanded answers about the "kidnap" on Saturday of Abu Anas al-Libi, who was indicted in connection with the 1998 bombings of US embassies in Kenya and Tanzania.

Somalia was more welcoming of the US Navy SEAL raid that took place on the same day thousands of miles away in the southern port of Barawe, with Prime Minister Abdi Farah Shirdon saying cooperation with foreign partners in the fight on terror was "no secret."

The success of that assault on the beachfront villa of a leader of Somalia's Al-Qaeda-linked insurgents was still unclear, with the fate of the target uncertain.

It came after last month's siege of an upscale shopping mall in the Kenyan capital Nairobi that left 67 people dead.

Defense Secretary Chuck Hagel said the operations sent "a strong message to the world that the United States will spare no effort to hold terrorists accountable."

"We will continue to maintain relentless pressure on terrorist groups that threaten our people or our interests, and we will conduct direct action against them, if necessary, that is consistent with our laws and our values."

Secretary of State John Kerry, speaking in Indonesia, said the United States would "never stop" in its battle on terror.

The operations showed that Washington "never forgets those who are victims of terrorism," National Security Council spokeswoman Caitlin Hayden said.

No US personnel were killed or injured in either operation, officials said.

The twin operations marked a contrast with "boots-on-the-ground" wars, which US President Barack Obama has vowed to avoid, and also from attacks using unmanned drones, a tactic which the United States has controversially pursued against extremists in Pakistan and Yemen.

Former military adviser Seth Jones of the RAND Corp. said that raids by special forces generally result in fewer civilian casualties than drone strikes while allowing for interrogation of suspects and seizure of items of interest.

"You can still accomplish many of the same objectives and collect the intelligence, and it will be a little less controversial" than drone strikes, Jones said.

The Pentagon said Libi -- who was on the FBI's most wanted list with a $5 million bounty on his head -- was being "lawfully detained under the law of war in a secure location" outside Libya.

Libi had been indicted in US federal court in New York for allegedly playing a key role in the east Africa bombings -- which left more than 200 dead -- and plots to attack US forces.

The Tripoli operation ended a 13-year manhunt for Libi, whose given name is Nazih Abdul Hamed al-Raghie.

His arrest paves the way for his extradition to New York to face trial. FBI and CIA agents assisted US troops in the raid, US media reported.

Citing surveillance camera footage, Libi's son Abdullah al-Raghie said his father had been seized by masked gunmen armed with pistols, and that some of them were Libyans.

He claimed the Libyan government was implicated in his father's disappearance, but Tripoli insisted the raid had no official authorization and demanded answers about the "kidnap."

In the Somalia raid, a US official said a "high-value" Shebab leader was the target, but according to The New York Times, SEAL commandos were forced to withdraw before confirming the kill.

The operation marked the most significant US assault in Somalia since commandos killed key Al-Qaeda operative Saleh Ali Saleh Nabhan in the same area four years ago.

"US personnel took all necessary precautions to avoid civilian casualties in this operation and disengaged after inflicting some Shebab casualties," the official said.

"We are not in a position to identify those casualties," the official said.

Leaders of the Shebab in Barawe, one of the few ports left in the hands of the insurgents, said commandos attacked from the sea and the air, but failed in their attempt to storm a house belonging to a senior commander and "fled" the scene.

"Our cooperation with international partners on fighting against the terrorism is not a secret," said Farah Shirdon, Somalia's prime minister.

"And our interest is to get a peaceful Somalia... free from terrorism and problems."