What’s important in all these cases is that low-intensity explosives were used. It is quite similar to what was found in Panipat — small amounts of potassium nitrate with sulphur, along with carbon and magnesium wires. All this was packed with either kerosene or petrol bottles lined up alongside in the suitcase. And covering all this were some clothes. Orpat digital watches were used as timers, just as in Malegaon. The explosion was small but enough to ignite a huge fire.

Sources say this underlines the recent trend among terrorists to use locally available material for making explosives but enough to cause widespread damage. Even in Malegaon, RDX was used in small quantities as the “core-explosive” with an aim to maximize the impact of the blast. The purpose: to throw off investigators by erasing the “signature.”

Given that this is the first major case where Pakistan nationals have been targeted on Indian soil, investigators are cautious about attributing the motive to Pakistan-based terror groups. At the same time, they are not ruling out the possibility of involvement of locals “handled” by individuals in Pakistan. Working on a few leads, including the two who are said to have got off from the train before Diwana, security agencies are working hard to ensure that this, too, doesn’t enter the list of inconlusive investigations into terror blasts.

As is always the case, several parallel forensic examinations are underway. Central security agencies, the National Security Guard, Haryana police and now even the Delhi police have collected material from the blast site.

There was some hope of a breakthrough after the detention of a Pakistani national, who had allegedly thrown one of the suitcases out of the train, but he let off by this afternoon as the police could not find anything against him. Moreover, the Pakistan High Commission had indicated its intention to seek consular access to him.

The Samjhauta explosion has also added a new dimesnion to India’s terror alert system. From now on, blasts and attacks in Pakistan will be watched carefully as they could resonate here as well, emphasising that both countries are a common target.

The first step in this direction was taken today when the Home Ministry, taking note of the suicide attack in a courtroom at Quetta, Pakistan, yesterday called for a review of security of courts here, this includes the Supreme Court and other high courts.

Meanwhile, Pakistan Foreign Minister Khurshid Mahmud Kasuri reached here today and visted the injured in Safdarjung Hospital. Kasuri, who will meet Prime Minister Manmohan Singh and his counterpart Pranab Mukherjee tomorrow, emphasised the need to not blame Pakistan for terrorism.

It’s learnt that the Pakistan delegation will bring up proposals for improved security on trains like the Samjhauta and theThar Express. New Delhi, on other other hand, feels security of trains in India is not a bilateral issue although it’s ready to offer whatever assurances are needed.