Thousands of demonstrators are participating in a massive march across Pakistan today, condemning the government’s decision to reopen the supply route into Afghanistan for US trucks. The protesters were organized by the Islamist group Difah-e Pakistan Council (DPC), and participated in by religious and political opposition groups.

Protests began in the city of Lahore and headed north to the capital of Islamabad, gaining momentum along the way. The plan is to gather the thousands of demonstrators in front of parliament on Monday.

Getting into Islamabad might not be so easy, however, as the Pakistani government has announced new “security measures” that would require any protesters to submit ID cards before being allowed in the city. Officials are threatening to arrest anyone believed to be a member of a “banned organization.”

Pakistan reopened the route to Afghanistan last week, after the US agreed to “apologize” for the November 26 attack on Pakistani bases which killed 24 soldiers. The Pakistani parliament had initially demanded that the US also agree to halt all drone strikes against the country, but the US refused and is continuing to launch such attacks. The DPC is angry both at this refusal, and insisting that it is religiously unacceptable to allow Pakistani soil to be used for the occupation of a neighboring Muslim country.