Andrew Buncombe: Well-trained, motivated and on the rise. But who are these militants?

The images are nothing short of terrifying. A dozen well-trained, well-armed men fanning out and taking up their positions with consummate ease and expertise. Nothing could be more different than the grainy CCTV footage of a single truck lurching up to the gate of a five-star hotel and its driver arguing with the security guards and, five minutes later, a massive bomb exploding.

Last night, as Pakistani police continued what increasingly seemed a hapless hunt for the perpetrators of the Lahore attack, a consensus was gathering that the ambush represented the emergence of a new and distressing terror threat for South Asia.

It is not that militant attacks are anything new for Pakistan. Since the summer of 2007, the country has been beset by about 120 suicide bomb attacks on police and civilian targets. But almost without exception, they have been largely crude, hit-or-miss strikes that depended on one or two attackers delivering a truck or car bomb. Tuesday's highly-mobile, commando-style militants armed with grenade launchers and automatic weapons and who slipped away when they realised their objective was not obtainable, appeared anything but crude.

"These were definitely different tactics. They were like commandos and they were very clearly not on a suicide mission," said Ayesha Siddiqa, an Islamabad-based analyst and author. "They had a particular intention – to either kidnap or attack the Sri Lankan team – but when they were not able to do that they fled and have not been seen."

Many have likened the Lahore attacks to those in Mumbai last November when a similar number of well-trained, well-armed militants held off Indian counter-terrorism commandos for more than 60 hours. Those attacks were blamed by India and others on the Pakistan-based group Lashkar-e-Toiba (LeT). It is too early to say whether the LeT was responsible for the Lahore attack and experts point out that, in its 20-year existence, the LeT has never attacked a target inside Pakistan. But clearly something very serious is happening in Pakistan; someone, somewhere is training groups of well-equipped, highly motivated militants who have the wherewithal and skills to challenge even the best of the region's counter-terrorism forces. It raises all manner of questions; where are they being trained, who is supplying them with arms, who is supplying them with intelligence, why are the intelligence agencies such as Pakistan's notorious ISI not aware of this group? More sinisterly, many will ask, are elements in the ISI linked to these militants.

Diving into the alphabet soup of potential suspects for Tuesday's attack may be a futile task. Bahukutumbi Raman, an Indian security analyst and former intelligence official, said he believed a number of Pakistan-based militant groups had the potential to carry out that style of attack. They include the Harkat-ul-Mujahideen (HUM), the Jaish-e-Mohammad (JEM), an offshoot of the HUM, the Lashkar-e-Jhangvi (LEJ), an anti-Shia organisation, and the Harkat-ul-Jihad-al-Islami (HUJI).

Writing on his website, he adds: "Al-Qa'ida and the [Pakistan Taliban] have carried out a number of suicide bombings through individual suicide bombers and vehicle-borne bombers in many towns including Lahore but they have not so far carried out a frontal urban ambush ... Since its formation in 1989, [the LeT] has never carried out any act of terrorism in Pakistani territory, against Pakistani or foreign nationals. All its acts of terrorism have been either in Indian or Afghan territory."

Mr Raman says the HUM once had operational ties with the Liberation Tigers of Tamil Eelam (LTTE) the Sri Lankan rebel group.

The incident has also forced a rethink of what constitutes a target. Until this point, sportsmen and woman were believed to be largely insulated from the region's extremism. But if cricketers are now considered fair game, it means, in effect, that no one is safe.

Asked how Pakistan can defend itself against this new threat, Talat Masood, a former Pakistani general, said: "You have to have a lot of good intelligence, the support of your people and a better police. You also have to have good governance, rather than growing opposition to everything that is happening."