ISLAMABAD, Pakistan -- A long-awaited ground offensive to drive Taliban insurgents out of Pakistan's lawless tribal areas is expected within weeks after hush-hush visits by top U.S. officials.
Airstrikes targeting hideouts belonging to the Pakistani Taliban have killed dozens of suspected militants in North Waziristan since late last week.
The raids came just days after a quiet trip to Pakistan by CENTCOM chief Gen. Lloyd Austin III on Feb. 19. CIA Director John Brennan arrived on Feb. 21.
Analysts believe the daily strikes by Pakistani helicopter gunships and fighter jets -- including many provided by the U.S. -- are intended to build momentum ahead of an attack involving thousands of Pakistani troops in the largely ungoverned tribal belt that straddles the Afghan border.
One senior Pakistani military source told NBC News that a "ground offensive by the military will be launched sometime in the middle of March" in volatile North Waziristan. Speaking on condition of anonymity, another Pakistani security source said the operation "will be any day now."
However, officials refused to discuss the plans openly due to its sensitive nature.
Daniel S. Markey, a senior fellow at the Council on Foreign Relations think tank, said Brennan and Austin's meetings at the military headquarters in Rawalpindi suggested high level of cooperation with Washington.
“A North Waziristan campaign is something the U.S. has been pushing for, for years,” Markey said.
The Pakistani Taliban has been blamed for the deaths of at least 40,000 civilians and 5,000 troops during its decade battling against the country's government. Pakistan's military has been clear about targeting elements of the group, which is the local offshoot of the Afghan insurgency.
Markey pointed out that Waziristan is also home to the Haqqani network – an Islamist insurgent group loyal to the Afghan Taliban, who have waged war on both Afghanistan’s government and U.S.-led NATO forces in the country. They are also believed to be holding Bowe Bergdahl, the only U.S. solider missing in the war in Afghanistan.
One senior official involved in planning counter-insurgency operations in Afghanistan last year described the Haqqanis as the "most dangerous and capable group within the larger Taliban movement" and the "most successful" militants in the region.
The Haqqanis have long used Waziristan as a sanctuary, with protection from the Pakistani state, raising the question of whether that group will be targeted during the looming ground offensive.
In a bid to coordinate efforts against the Haqqanis before foreign combat troops depart later this year, the U.S. has set up a unit made up of Special Forces, conventional forces and intelligence personnel, known as a “fusion cell” in Kabul, Reuters reported this week.
"Things are coming together in terms of the more comprehensive approach [against the Haqqanis]. So, there's a lot of focus - there's a lot of energy behind it right now," a U.S. defense official told Reuters.
A Pakistani intelligence official told NBC News that "Bergdahl's release is not a top priority in the security matrix of the fight in the tribal areas," indicating the diverging interests of the U.S. and Pakistani forces in the region.
Sending Pakistani troops into the semi-autonomous and volatile North Waziristan would be fraught with peril, according to Markey. He said they would not only face an organized insurgency, but one with significant military capabilities.
The region was traditionally managed by a tribal structure but that has broken down over the last decade because younger Taliban commanders have assassinated elders and assumed power, Markey said.
“These are young men who rule by the gun,” he added. “They're quite prepared to fight to the death.”
The Pakistani Taliban has an estimated 15,000 to 20,000 hardened fighters in North Waziristan, according to an officer of the country's 7th Infantry Division who recently spoke exclusively to NBC News.
Many previous attempts to dislodge militants from the area have been unsuccessful, according to Gareth Price, a senior research fellow at the London-based Chatham House think tank.
“Since 2004 and 2005 you've had campaigns that haven't been holistic or coordinated,” he said. “Often they just look like a facade with people firing mortars at empty mountainsides because the insurgents have moved on to the next tribal area, ready to return when the army leaves.”
Outrage about the recent execution of 23 soldiers held by the Pakistani Taliban since 2010, at the same time the country’s government was engaged in peace talks with the militants, appears to have steeled the military's resolve, Price said.
However, he wondered whether Pakistan had enough military personnel in the area to launch a concerted campaign that would stop the militants escaping as they have in the past.
“It would take a lot of troops to flush out all the militants,” he said.
However, Major General Asim S. Bajwa, spokesperson of the Inter-Services Public Relations Directorate of the Pakistan army, told NBC News that “over 150,000 troops are committed to fighting the insurgency in the tribal areas, compared to less than 100,000 on the Indian border, which reflects our resolve about how seriously we are taking this new, internal threat.”
Bajwa added: "Over the years, we have cornered the terror elements ... in North Waziristan. Now, all we have to do is mop them up."
The CIA has conducted hundreds of drone attacks in Pakistan’s tribal areas, especially North Waziristan, since 2004. But they were suspended by the U.S. almost two months ago as peace talks between Pakistan and the country's Taliban got under way.
The visit of CIA chief Brennan was reportedly linked to spelling out the rules of engagement if U.S. drones based in Afghanistan were to be used during the ground operation.
One senior Pentagon official told NBC News that "we always have eyes on the border."
Jim Miklaszewski of NBC News contributed to this report. Henry Austin reported from London.