Kabul, Afghanistan (CNN) -- Another Taliban leader has been seized in neighboring Pakistan by security forces, sources said.
Mullah Abdul Salam was arrested last week, according to Afghan government officials, Taliban sources and a U.S. official.
Word of Salam's arrest comes days after news of the capture of the Afghan Taliban's reputed second-in-command, Mullah Abdul Ghani Baradar.
"The Taliban is down another 'shadow governor,' " the American source said of Salam. The source declined to be named because of the sensitivity of the information.
The news came against the background of an intensified U.S.-led campaign against insurgents on both sides of the border.
Taliban fighters are resisting Operation Moshtarak, an allied military push into areas the Taliban control in southern Afghanistan's Helmand province.
"They know this is their last stronghold. They're not backing down," CNN's Atia Abawi reported from the battlefield, where she is embedded with U.S. Marines.
The crackle of small-arms fire and the whoosh of outgoing mortar rounds from the Marines were clearly audible on the line as she described the battle.
"About five minutes ago, Taliban started attacking our area," she said shortly before 8 a.m. ET. "The Taliban are not giving up -- they seem to be coming out in squads, [but] they know they can't group together in large numbers" because it would make them easier targets.
The Taliban seem to include "foreign fighters who will fight to the death," she said.
It will take NATO-led military forces "another 25 to 30 days to secure that which needs to be secured" in Helmand and a further three months to ensure insurgents are kept out of the area, British Maj. Gen. Nick Carter said Thursday in a briefing from Afghanistan broadcast by the Pentagon Channel.
The Nad-e Ali district is "broadly secure," Carter said, noting there is still Taliban resistance in Marjah.
"It will be some days before we can be completely confident that Marjah is secure," said Carter, the International Security Assistance Force's head of Regional Command South.
Ten civilians were killed on the second day of the operation, he said. Reports at the time said 12 were killed.
There have been five casualties among the NATO-led forces during the operation, the forces said in a statement Thursday, without giving further details.
It said later that four ISAF servicemembers died Thursday -- two of them in an improvised explosive device strike; another after a separate IED attack; small-arms fire killed the fourth servicemember. It was not immediately clear whether the four were among the five casualties noted earlier. The four deaths bring to 44 the number of Americans killed this year in Afghanistan. In all, 78 coalition forces have died this year
Across the border in Pakistan, four people were killed and five were wounded Thursday when a drone fired on a suspected militant compound in the country's tribal region, intelligence sources and a local political official said.
The four dead were suspected militants, two intelligence officials said. It was not clear whether the wounded also were militants.
The remote-controlled aircraft fired two missiles at the compound in the Danday Darpakhel area of North Waziristan, one of seven districts in the tribal region along the Afghan border, the sources said. They asked not to be identified because they are not authorized to speak to the media.
The U.S. military does not comment on reported attacks by the pilotless aircraft, but the United States is the only country operating in the region known to have the ability to launch missiles from drones.
Salam was arrested in Pakistan, the Afghan government and Taliban sources said, but they named different cities as the location of his capture.
Gov. Muhammad Omar of Afghanistan's Kunduz province said Salam was detained in Quetta, where the Afghan Taliban reportedly has its leadership councils. The Taliban sources said he was nabbed in Faisalabad.
Salam is believed to be the Taliban commander for Kunduz, Omar said.
Salam was directing Taliban military operations in the province, including ordering terrorist actions, mine planting and suicide attacks, said Abdul Razaq Yaqubi, police chief in Kunduz.
Yaqubi said Salam and another Taliban "shadow governor," Mullah Salih, were arrested last week in the Pakistani city of Peshawar. He said the information came from Pakistani authorities.
Salih was the shadow governor of Baghlan province, the police chief said. There was no immediate confirmation of Salih's arrest.
Taliban sources and Omar said other suspected members of the Afghan Taliban were arrested with Salam, but their identities are not clear.
CNN's Pam Benson in Washington and journalist Mati Matiullah in Kabul contributed to this report.