LAHORE, Pakistan — Thousands of hard-line Islamists streamed toward Pakistan’s capital in a massive convoy of vehicles Sunday to protest the government’s decision to allow the United States and other NATO countries to resume shipping troop supplies through the country to Afghanistan.

The demonstration, which started in the eastern city of Lahore, was organized by the Difah-e-Pakistan Council — Defense of Pakistan Council — a group of politicians and religious leaders who have been the most vocal opponents of the supply line.