According diplomats, the Americans are now trying to secure three different alternative supply routes for Afghanistan. The first one is the northern route which starts in the Latvian port of Riga, the largest all-weather harbor on the Baltic Sea, where container ships offload their cargo onto Russian trains. The shipments roll south through Russia, then southeast around the Caspian Sea through Kazakhstan and finally south through Uzbekistan until they cross the frontier into north Afghanistan. The Russian train-lines were built to supply Russia's own war in Afghanistan in the 1980's, and these can be used by the US-led forces in their own Afghan campaign.
The second one is the southern route which transits the Caucuses, completely bypassing Russia, from Georgia. Starting from the Black Sea port, Ponti, it travels north to Azerbaijan and its port, Baku, where goods are loaded onto ferries to cross the Caspian Sea. Landfall is Kazakhstan, where the goods are carried by truck to Uzbekistan and finally Afghanistan. While shorter than the northern route, it is more expensive because of the on-and-off loading from trucks to ferries and back onto trucks. A third supply route, which is actually a spur of the northern route, bypasses Uzbekistan and proceeds from Kazakhstan via Kyrgyzstan and Tajikistan, which has a north east border with Afghanistan. However, this route is hampered by bad road conditions in Tajikistan.
Yet there are those in the Pakistani security establishment who think that it would be hard for the Americans to induce any of the former Russian states for the NATO supplies because many of their leaders believe that the American plans to get military supplies via their countries could draw the former Soviet colony into the battle as Cambodia was dragged into the Vietnam war. But diplomats say NATO is already using some alternate supply routes after a string of disruptions caused by the Pakistani authorities. As recently as July 2011, these circles say, the balance of supplies transiting through Pakistan and the northern distribution network were weighted in Pakistan's favor, with more than half of ground-transported supplies arriving through Pakistan. But the situation has changed with the US deciding that only 25% of ground cargo should arrive via Afghanistan's eastern neighbor.
http://www.atimes.com/atimes/South_Asia/MK30Df01.html