MIRANSHAH, Pakistan | 
 
 MIRANSHAH, Pakistan (Reuters) - Missiles fired from unmanned U.S. aircraft killed at least four militants in Pakistan on Wednesday, officials said, ending an eight-week pause in the use of a tactic that has become a mainstay of the fight against insurgents. 
 
 Drone attacks have been used increasingly in recent years in the fight against insurgents in Pakistan's largely lawless Pashtun tribal areas in the west and northwest who fuel violence across the border in Afghanistan. 
 
 Pakistani security and intelligence officials said the missiles hit a home on the outskirts of the town of Miranshah in North Waziristan, killing at least four militants. 
 
 Insurgents often dispute official versions of such attacks and the death tolls involved. 
 
 The strike was the first such attack since November 17 and could deepen anti-U.S. sentiment in Pakistan, which was already running high after a November 26 cross-border NATO air attack that inadvertently killed 24 Pakistani soldiers. 
 
 "I think we were expecting the drone strikes after a long break," said Amir Rana, director of the Pakistan Institute for Peace Studies. "There were even a few reports were coming from the last two, three days that they are going to be resumed." 
 
 The November 26 air strike triggered a deep chill in already troubled U.S.-Pakistan relations, prompting Pakistan to close off NATO supply routes into Afghanistan. 
 
 A source in Washington confirmed that a U.S.-operated drone had been fired at a militant target in Pakistan on Wednesday. The source said no well-known militants were believed to have been targeted or wounded in the attack. 
 
 Drones armed with missiles have played a significant role in U.S. counter-terrorism operations as the Obama administration winds down the war in Afghanistan and Washington's focus expands to militant havens in countries including Pakistan. 
 
 The United States vacated a remote air base, used to stage classified drone flights against militants, in Pakistan's southwestern Baluchistan province last month. Pakistan had asked U.S. forces to leave the base after the November air strike. 
 
 The Obama administration contends that drone strikes have helped weaken the central leadership of al Qaeda and put associated militant groups on the defensive. Others said the lull since mid-November had allowed militants to regroup. 
 
 "The militants were quite happy with this lull and they were publicly operating in the region as they were no more worried for their lives," a security official in the region told Reuters. 
 
 Many militant groups operate in Pakistan's tribal areas. 
 
 U.S. officials denied the drop-off in lethal drone attacks was part of a deliberate moratorium on such flights linked to the political and diplomatic uproar over the November air strike. 
 
 Officials maintained that lethal drone strikes were based on the availability of targeting intelligence and implied that such intelligence had been in short supply recently. 
 
 The latest drone strike in Miranshah appears to demonstrate that if there was any kind of moratorium on such attacks, it has now been lifted. 
 
 (Additional reporting by Saud Mehsud in DERA ISMAIL KHAN, Qasim Nauman and Rebecca Conway in ISLAMABAD, and Mark Hosenball in WASHINGTON; Editing by Paul Tait) 

 An American drone strike killed four Islamist militants in Pakistan, the first such attack since errant U.S airstrikes in November killed two dozen Pakistan troops and pushed strained ties between the two nations close to collapse, Pakistani intelligence officials said Wednesday. 
 
 The attack Tuesday took place in North Waziristan, an al-Qaida and Taliban stronghold close to the Afghan border that has been pounded by U.S. strikes, the officials said. Three of the dead were Arab fighters, said the officials, who didn't give their names because they were not allowed to be named in the media. 
 
 The late-night missile launch broke the longest pause between strikes since the drone program began in earnest in 2009. 
 
 American officials say there had been no promise by Washington to avoid drone operations since the deadly Nov. 26 airstrikes along the Afghan border, but that the lull was part efforts to tamp down tensions with Pakistan, seen by many U.S. officials as key to a negotiated peace in Afghanistan. 
 
 After the American strike, Islamabad shut down vital supply routes into Afghanistan and forced the U.S. to vacate Shamsi Air Base in southwestern Baluchistan province. The U.S. used the base to service drones that targeted militants in the tribal regions close to Afghanistan. 
 
 While there has been some level of Pakistani acquiescence to the drone program, the attacks are extremely unpopular with the public, and their scope and frequency has been a source of friction between the two countries. 
 
 It was unclear whether the U.S. had given any indication that it would resume strikes, or whether the fresh attack would hamper American efforts to rebuild cooperation with Islamabad and reopen its supply routes. 
 
 The missiles struck a house around two kilometers from Miran Shah, the main town in North Waziristan, shortly before midnight locals said. "It was an unusually big bang. Since it was extremely cold I didn't leave the house, but could see a house on fire," said Qasim Noor, a 20-year-old college student. "In the morning, we saw a modest mud house had been destroyed." 
 
 A U.S. official confirmed there had been a missile strike in the region. 
 
 An American investigation into the November airstrikes concluded that a persistent lack of trust between the U.S. and Pakistan, and a series of communications and coordination errors on both sides, led to the attacks. Pakistani officials have rejected that probe and there has been little public sign that relations between the two countries are improving. 
 
 There were more than 60 drone attacks last year, significantly less than in 2010. The attacks have killed scores of militants, among them several mid- and high-ranking commanders. American officials don't talk about the program in public, but privately say it has been vital in countering the threat from al-Qaida in one of its global hubs. 
 
 Human rights activists in Pakistan and abroad have reported significant civilian casualties as a result of the strikes. The U.S. says the strikes are accurate, but doesn't publicly investigate the allegations. 
 
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 Lolita Baldor reported from Washington.
– The US' drone war in Pakistan is back on. The US launched its first strike last night since a November attack that killed 28 Pakistani soldiers and ratcheted the already fraught tensions between the two nations to a new high. The attack hit a North Waziristan home just before midnight, killing at least four, the AP reports. "It was an unusually big bang," one local college student says. "In the morning, we saw a modest mud house had been destroyed." So far there's no indication if the US cleared the strike with Islamabad. Despite the long pause since the controversial attack, US officials tell Reuters that there was never a deliberate moratorium on drone strikes, instead implying that it had simply lacked sufficient intelligence to launch any.