Islamabad , Pakistan ( CNN ) -- A protest march against U.S. drone strikes in Pakistan , led by former cricket star turned politician Imran Khan , came to a halt on Sunday when authorities blocked access to the demonstration 's final destination in the tribal region , officials told CNN . Authorities used steel shipping containers and security forces to seal off the road entering South Waziristan , where protesters had planned to hold a rally on Sunday , local government official Shahid Ullah said . When confronted with the roadblock , Khan directed protesters to turn back , saying the march had achieved its goal of drawing attention to the controversial U.S. drone strikes . Khan has been a fierce critic of U.S. policy in Pakistan and the use of drone strikes , calling them a violation of Pakistan 's sovereignty and a strategy that fuels militant anger towards Washington . `` We will not cause any trouble if the government does n't want us to enter South Waziristan , '' Khan told reporters . `` We just want to direct the attention of the entire world to these illegal and immoral drone attacks in Waziristan that have left many innocent people dead . '' In recent years Washington has sharply stepped up the use of drone attacks in Pakistan 's mostly ungoverned tribal region , widely believed to be a safe haven for militant groups fueling the insurgency in Afghanistan . U.S. officials say the drone strikes are an effective strategy against militant groups and insist civilian casualties are rare . The anti-drone march set out in a convoy of more than 100 vehicles from the capital , Islamabad , on Saturday and reached the border of South Waziristan on Sunday afternoon , where it was turned back . The U.S.-based anti-war group Code Pink was part of the procession . Throughout the journey the pink-clad peace activists regularly chanted anti-drone slogans in Pakistan 's native language of Urdu . `` Stop them ! Stop them ! Stop the drone attacks , '' the protesters shouted in Urdu . Pakistani authorities had earlier warned that the demonstration would not be allowed to enter South Waziristan for security reasons . `` The situation in the tribal areas is comparatively good but not suitable for any gathering there , '' Tashfeen Khan , a government official , said on Saturday . Journalist Aamir Iqbal contributed to this report .
Authorities block road into South Waziristan , ending protest march . - Pakistan government announces that it will not allow any foreign troops to enter the country until a new constitution is written and implemented. Officials say demonstrators were kept out of South Waziristan for security reasons . March was led by former cricket star turned politician Imran Khan .