The United States military has halted cargo movement through Pakistan after large scale protests in the country against U.S. drone strikes. The route, from Torkham Gate at the Afghanistan-Pakistan border to the Pakistani port city of Karachi, is the key route for ground transport of military cargo. Although there are other routes, reports say, they are significantly more expensive.

Supporters of the Pakistan Tehreek-e-Insaf (PTI) political party of former cricket star Imran Khan protest during a rally to stop NATO supply routes into Afghanistan and drone attacks, in Peshawar November 23, 2013. Khan, whose political party is now in charge of the volatile Khyber Pakhtunkhwa (KP) province bordering Afghanistan, has threatened to cut NATO supply lines through his region from November 23 if U.S. drone strikes do not end. (REUTERS/Fayaz Aziz)

On Tuesday, Pentagon reportedly ordered truckers under U.S. contracts to avoid using the route following ongoing protests against drone strikes in Pakistan.

"We have voluntarily halted US shipments of retrograde cargo through the Pakistan Ground line of Communication (GLOCC) from Torkham Gate through Karachi," Pentagon spokesman Mark Wright said in a statement.

The Pentagon spokesman said suspension of transport on the route affected "retrograde cargo." This includes equipment and other goods which is being shipped home from military bases in Afghanistan as the U.S. begins troop pullout from the country scheduled to be completed by the end of 2014.

Reports say about half of U.S. cargo being shipped out from Afghanistan take the route through Pakistan. Although alternative routes do exist for the U.S. through Central Asian countries; they take longer and are more expensive.

Mr Wright added that the Pentagon expected to resume using the route though Pakistan "in the near future."

Pakistanis have all along resented U.S. drone strikes in their territory, terming it as a violation of the country's sovereignty.

The Pakistan's Tehreek-e-Insaf (PTI) political party of former cricket star Imran Khan has recently organised a major protest rally demanding a stop on NATO supply routes into Afghanistan and drone attacks, in Peshawar.

Pakistan has in the past shut U.S. routes through the country. It forced a seven-month closure of the route after U.S. airstrikes accidentally killed two dozen Pakistani soldiers in Nov. 2011.

The supply route was reopened in July 2012, following Washington's apology for the attack.