The issue violating two Chinese helicopters in spiti area of himachal Pradesh was today raised in Himachal pradesh assembly. The helicopters were spotted by personnel of the Indo Tibetan Border Police (ITBP), which is manning the border, around noon on 16 march .This is second incident of its kind in the last four months. Replying a call attention motion the Chief minister Mr. Prem Kumar Dhumal said that there have been reports of China strengthening military infrastructure along border areas close to Shipki, the main trading centre. Shigastay in China-controlled Tibetan autonomous region is the airbase closest to the Indian border.