NEW DELHI: Till not too long ago, the exact presence of Islamic State (ISIS) operatives was being debated. On Friday almost 20 ISIS operatives are in the dragnet of security forces as a result of a pan-India crackdown that has its roots in behind the scenes cooperation between Indian and US intelligence agencies.Highly placed sources said tip offs by US agencies, that are tracking ISIS computers and phones in West Asia, saw Indian agencies follow the leads over the last weekend that led them to blow the lid off the ISIS cells.Explaining the operation, a source said CIA is keeping a watch on hundreds of IP addresses of computers and smart phones being used by ISIS in Syria and Iraq. There were several addresses which ISIS operatives were using to access Facebook.All such IPs and proxy servers were under surveillance and one address was used by ISAuT commander Shafi Armar (codename: Yousuf al-Hindi) to communicate with the likes of Akhlaq ur Rehman (arrested in Haridwar aloing with three others) and several others. The inputs were being shared and surveillance mounted on the suspects.\Sources say the agencies were able to intercept calls and Whatsapp and Facebook messages being exchanged by the arrested operatives.In mid-January, an exchange between Yousuf and Akhlaq read — 7 kalash rakh do. The code was interpreted as a plot to bomb seven places.This input was shared by CIA with Indian agencies and alarmed security officials briefed national security adviser Ajit Doval.In the next few hours, the suspects shifted from Roorkee to Haridwar. The sleuths were all charged up anticipating the next move. They knew a strike was in the making. After five hours, the suspects in Haridwar shifted base to Roorkee after conducting a survey . Similarly, other modules also seemed to act in a suspicious manner. A crackdown on all known ISIS modules across India was ordered.Agency sleuths worked against time and roped in police and anti-terror squads stationed in Delhi, Bangalore, Mumbai and Hyderabad. A control room was set-up in Delhi as field officers and policemen spread at their respective target places. Nobody had an idea of the identity of the target and were only briefed about the name and place of stay of the person.Through Saturday and Sunday, the agencies executed the operation and picked up the suspects. The Roorkee-Haridwar operation happened before agencies suspected a strike even sooner than other modules. Once they were detained, all suspects were picked up one by one. The north Indian module was handed over to the special cell which had already been tracking them. The others were handed over to the NIA and other police.