International forces also pressed forward with a key combat operation in their drive to rout Taleban fighters around the southern city of Kandahar, a push that is key to US military strategy to turn around the 9-year war and prevent the Taleban from undermining the Afghan government.
The airstrikes into Pakistan came after the insurgents attacked a small Afghan security outpost near the border.
NATO justified the strikes based on "the right of self-defense," a spokesman said. Pakistan is sensitive about attacks on its territory, but US officials have said they have an agreement that allows aircraft to cross a few miles (kilometers) into Pakistani airspace if they are in hot pursuit of a target.
The first strike took place Saturday after insurgents based in Pakistan attacked the outpost in Afghanistan's eastern province of Khost, which is located right across the border from Pakistan's North Waziristan tribal area, said US Capt. Ryan Donald, a spokesman for the NATO-led International Security Assistance Force in Afghanistan.
"The ISAF helicopters did cross into Pakistan territory to engage the insurgents," Donald said. "ISAF maintains the right to self-defense, and that's why they crossed the Pakistan border." The strike killed 49 militants, said US Maj. Michael Johnson, another ISAF spokesman. NATO officials were able to assess the number of militants killed in the airstrikes by using gun cameras mounted on the helicopters, according to ISAF.
Abdul Hakim Ishaqzie, the provincial police chief in Khost, cited a higher death toll of around 60 militants. He said police at checkpoints at the border came under attack, engaged the miliants in a gun battle and then called for help, prompting the helicopter strikes.
The air strikes occurred on the Pakistan side as militants fled, but police said they were able to go in and count the bodies.
"It was a very effective operation against the militants," said Ishaqzie. "Around 60 militants were killed. Police forces collected ammunition and weapons from the battlefield." The second attack occurred when helicopters returned to the border area and were attacked by insurgents based in Pakistan, Donald said. It killed at least four militants.
"The helicopters returned to the scene and they received direct small arms fire and, once again operating in self-defense, they engaged the insurgents," Donald said.
Pakistani intelligence officials said two NATO helicopters carried out a third strike inside Pakistani territory on Monday morning, killing five militants and wounding nine others.
The strike occurred in the village of Mata Sanger in the Kurram tribal area, which is directly across the border from the Afghan provinces of Paktia and Nangarhar, said the officials, speaking on condition of anonymity because they were not authorized to talk to the media.
NATO would not immediately confirm that.
While airstrikes by unmanned US drones believed operated by the CIA against Al-Qaeda and Taleban targets are common inside Pakistan's tribal regions, particularly North Waziristan, major strikes using manned aircraft are rare.
On Monday, a suspected US missile strike killed four people near Mir Ali, a major town in the North Waziristan, Pakistani intelligence officials said on condition of anonymity because they were not authorized to talk to the media. It was the 20th such attack this month.
In south Afghanistan, meanwhile, international and Afghan forces were moving into two or three areas around Kandahar at once to pressure the Taleban "so they don't get the chance to run away," Shah Mohammad Ahmadi, chief of Arghandab district northwest of the city, said Monday.
"Before, when we have tried to get rid of the Taleban, when we cleaned one area we found more Taleban in a different one," he said.
A top NATO officer said Sunday that the alliance a few days ago had launched a "kinetic," or combat, phase of "Operation Dragon Strike," a joint military push with Afghan forces around Kandahar intended to rid the area of insurgents and interrupt their ability to move freely and stage attacks.
"It is a significant ground operation with air support," German Brig. Gen. Josef Blotz, a NATO spokesman, said at a news conference. "We expect heavy fighting." "Afghanistan and coalition forces are destroying Taleban positions so they will have nowhere to hide," Blotz said.
"Once this is done, insurgents will be forced to leave the area or fight and be killed." NATO said militants have fought back with rocket-propelled grenades and small-arms fire, but no Afghan or coalition troops were killed.
The push in Kandahar is seen as key to the Obama administration's strategy to turn around the war as insurgents undermine the ability of an Afghan government to rule much of the country. Kandahar remains particularly dangerous; seven US troops have been killed in Kandahar this month. Another three have been killed in the south, but no further details have been released.
"First, they are clearing the area of Taleban and then they are searching the area for mines," said Kareem Jan, district chief of Zhari, west of Kandahar.
In another volatile section of the nation, British officials said Monday that they were in contact with Afghan authorities about the disappearance of a British aid worker and three of her Afghan colleagues. The four were ambushed Sunday as they traveled in two vehicles in northeastern Kunar province. Police fought a gunbattle with the kidnappers near the attack site before the assailants fled, Kunar police chief Khalilullah Zaiyi said.
The British Embassy in Kabul said officials were working closely with all relevant local authorities and said the worker's family had been contacted.
Steven O'Connor, communications director for Development Alternatives Inc., a global consulting company based in the Washington, D.C., area, said late Sunday its employees, including a British national, were involved. The company works on projects for the US Agency for International Development in Afghanistan.
Also Monday, Poland's military said a Polish soldier died of injuries sustained when a land mine exploded under his patrol vehicle in the eastern province of Ghazni. He was is the 21st Polish soldier to die in Afghanistan. Poland has some 2,600 troops in the country.
