DIYARBAKIR, Turkey, May 7 (Reuters) - Turkish troops backed by helicopters have launched an operation against Kurdish separatist rebels, security sources said on Monday, after two soldiers and five rebels were killed over the weekend. They said thousands of soldiers were taking part in the operation involving Cobra and Sikorsky helicopters against rebels from the outlawed Kurdistan Workers Party (PKK) in the valleys of mountainous Sirnak province, near the Iraqi border. Fighting escalates in the spring as the snow melts and rebels cross the border from mountain bases in Kurdish-ruled northern Iraq, where Ankara continues to urge the United States to crack down on militants. The sources said security had been stepped up along the border with Iraq, which was being monitored by F-16 warplanes during the day and thermal cameras at night. More than 30,000 people have died in the conflict between Turkey and the PKK since it launched its insurgency for a homeland in the mainly Kurdish southeast in 1984.
