Local media say thousands of Pakistanis, joined by US anti-war activists, are heading toward Pakistan's militant-riddled tribal region to protest US drone strikes, despite threats of suicide attacks by the Pakistani Taliban.
After an overnight stay, the motorcade led by cricketer turned politician Imran Khan departed for the town of Tank near the tribal belt.
The US says its drone strikes are aimed at militants, but Pakistan charges they violate its sovereignty and kill civilians.
Video on Pakistani media showed barricades with hundreds of police in riot gear. It appeared unlikely the protesters would be allowed to reach South Waziristan for a rally.
In a televised speech, Khan thanked his supporters and the US group, declaring they achieved their goal of sending a message to the world against drone strikes.