Guwahati : Following the attacks on the World Trade towers and the Pentagon by terrorists last week, there is a state of heightened alert in Assam following reports that the ISI may step up attacks.H K Deka, DGP, Assam, stated, "We are also facing a grave threat particularly because of the organizations which are very active in this region. There are several outfits which have got connections with the enemy states."Security at vital instillations including airports and oil stations has been beefed up. There is also constant patrolling along the more than 1,000 km long oil pipeline from Duliajan in Upper Assam to Barauni in Bihar.The next few days will be tense for security forces in Assam, a state that on any given day is constantly under threat.