ISLAMABAD – Thousands of Pakistanis joined by a group of U.S. anti-war activists headed toward Pakistan's militant-riddled tribal belt Saturday to protest U.S. drone strikes – even as a Pakistani Taliban faction warned that suicide bombers would stop the demonstration.

The motorcade march was led by Imran Khan, an ex-cricket star-turned-populist politician who heads the Pakistan Tehreek-e-Insaf party. Militants have dismissed Khan as a tool of the West despite his condemnations of the drone strikes, which have killed many Islamist insurgent leaders.

Pakistanis in small towns and villages along the roughly 250-mile route warmly welcomed the 150-plus vehicle convoy. Footage broadcast on Pakistani TV showed people showering rose petals on the motorcade. But by late Saturday, it appeared increasingly less likely the protesters would reach their ultimate destination, the South Waziristan tribal area, where they hoped to stage a major rally.