The U.S. has shifted its Afghanistan supply lines to the north, bringing freight in via rail, from Baltic Sea ports, through Russia and Central Asia. While negotiating these arrangements, the United States also approached China, which also borders Afghanistan. But this is an odd border. It is reached through a long, narrow panhandle (the Wakhan Corridor), and the actually border with China is only 76 kilometers long. The Wakhan Corridor area has never been very violent, and escaped most of the fighting that has torn apart Afghanistan since the 1970s. But China refused to open its border with Afghanistan, fearing complications with the mainly Moslem population on their side of the frontier.
But the U.S. kept after China about this, and Google Earth images have shown that China has recently built a new road to the area and additional guard posts. The Wakhan Corridor itself was once part of the Silk Road, but snow closes a key pass for five months a year. The Chinese Wakhan Corridor border has been closed to traffic for over a century.
China has since said that it is reconsidering opening the border, but a sturdy road would have to be built along the length of the 210 kilometer long corridor, before significant freight could be brought in via China. The border would be opened more for the purpose of fostering trade, than to support the NATO war effort.