NATO supplies into Afghanistan had been suspended, but now they are being resumed. The wait was on a US-Pakistan deal that would stop the Islamabad blockade, which was preventing the US military moving into Afghanistan with the NATO supplies.
These supplies are being protected by US military moves. Without the military the supplies could be raided, so to make certain the drivers are all safe the convoys are being protected. The truckers, even before the supply chain resumed, asked for more protection. Drivers and the other workers who had to sit idle due to the stoppage of the convoys are now prepared to get back to work.
Hilary Clinton made the announcement that the blockade would end and that those in need of help would be able to get it. She also made a statement that the US is sorry for military losses in Pakistan. Pakistan has provided the drivers and the military protection. In addition to these losses there was an issue with a US airstrike, which accidentally killed 24 Pakistani soldiers near the Afghan border last year. It was this issue that caused the supply lines to close in the first place. Pakistan wanted a full apology after the incident, which was offered Tuesday.
NATO can now enter and exit Afghanistan through Pakistan or Central Asia. Central Asia is more expensive though, which is why a move for Pakistan was made. The movement of vehicles will resume as soon as the trucks are loaded.