Suspected Naga militants set afire nine tankers loaded with crude oil in the remote Namsik area on the Assam-Arunachal Pradesh border on Tuesday evening.The tankers were moving from Kharsang in Arunachal Pradesh to Digboi in Assam when they were set on fire near Jagun.Senior police and Army and Assam Rifles personnel rushed to the area, where security has since been beefed up."Nine oil tankers were set on fire. We suspect that National Socialist Council of Nagaland (Khaplang) militants are behind the incident since the anti-talks faction has a strong presence in the area along the inter-state border," a senior police official said.Tinsukia district in eatern Assam bordering Arunachal Pradesh has been witnessing militant activities in the recent past. While the anti-talk faction of Ulfa militants had killed a Bharatiya Janata Party leader and his son in the district after suspecting them to be spying for the Army, the Ulfa last month abducted a businessman's son who was later released.