Any links between Pakistan's Taliban and a failed bombing in New York's Times Square could put the country under renewed US pressure to open risky new fronts against Muslim militants. Tehrik-e-Taliban Pakistan (TTP), the Taliban Movement of Pakistan, has claimed responsibility for the failed bombing and its leader, Hakimullah Mehsud, appeared in videos on the Internet on Sunday threatening suicide attacks on major US cities. A US citizen born in Pakistan, Faisal Shahzad, is accused of driving the failed car bomb into Times Square and will appear in Manhattan court on Tuesday, authorities said. Questions may arise again over Pakistan's determination to tackle militants as it juggles other problems, from a sluggish economy to power cuts that have made the government unpopular. “Pakistan may have to prepare to make more sacrifices and wage a much more intense use of force such as search and destroy operations, more systematically,” said Rifaat Hussain, head of the Department of Defense and Strategic Studies at Quaid-i-Azam University in Islamabad. Pakistan, heavily dependent on foreign aid, says it is too stretched to expand security offensives to new areas such as North Waziristan, home to a complex web of militant groups that could deepen the threat to the state if antagonised. “International goodwill is going to sour unless we are seen to be doing more against the groups in North Waziristan and the groups of Punjab which have not been touched,” said Taliban expert and Pakistani author Ahmed Rashid. Some of Pakistan's most dangerous militant groups are based in the country's heartland Punjab province. They include Lashkar-e-Taiba (LeT), blamed for the 2008 attack on the Indian commercial capital Mumbai which killed 166 people and accused of plotting attacks in the West. LeT – once nurtured by Pakistan's Inter-Services Intelligence (ISI) agency to fight India in Kashmir -- is estimated to have between 2,000-3,000 gunmen and another 20,000 followers, many trained to fight and who could be mobilized against a crackdown. A major assault could drive the LeT and other Punjab groups into an alliance with the Pakistani Taliban, an umbrella group backed by Al-Qaeda that continues to stage suicide bombings despite offensives the army says have killed hundreds of fighters. Those risks may be put aside by the United States now that the failed Times Square bombing has sounded new alarm bells in a country still haunted by Al-Qaeda's September 11, 2001 attacks. If the United States pushes Pakistan too hard, it could strain relations that have improved in recent months. “If Hakimullah is responsible for what happened in Times Square and is launching a campaign against American cities, then this is the kind of thing that shakes everybody up and generates political will to really get in the Pakistani government's grill,” said Brian Fishman, counterterrorism research fellow with the New American Foundation. “If Hakimullah is in any way providing direction to attacks on the US homeland, that changes the kind of influence the US is going to want to assert against Pakistan. That raises the stakes of the political game.” Many security experts are skeptical the TTP has the ability to stage attacks outside Pakistan, but worry it may be growing closer to Al-Qaeda and could be adopted the global aims of Osama Bin Laden instead of limiting itself to fighting the Pakistani state. The United States has repeatedly called on Pakistan to do more to fight not just homegrown militancy but also Al-Qaeda-backed Afghan Taliban based in North Waziristan who cross the border to attack Western forces in Afghanistan. Pakistan has said it does not have the resources to go after other groups such as the Haqqani network, described by US forces as one of their biggest enemies in Afghanistan. There are strategic reasons for Pakistan's hesitancy to attack the Haqqanis, believed to operate from North Waziristan. Pakistan sees the group as a strategic asset that will give it influence in any peace settlement in Afghanistan so Islamabad will want those militants on its side.