Gurbanguly Berdymukhammedov is on a visit to neighboring Uzbekistan, which earlier agreed to allow the land transit of U.S. supplies through its territory to its war-torn southern neighbor.
"We do not mind the transit of [U.S.] humanitarian cargo through our air corridor," the Turkmen president said.
Due to worsening security on the main land route from Pakistan and the upcoming closure of a U.S. airbase in Kyrgyzstan, NATO has to rely on alternative routes to supply the U.S.-dominated International Security Assistance Force (ISAF) in Afghanistan.
There are over 60,000 foreign troops in Afghanistan, more than half of them from the United States, and U.S. President Barack Obama has recently ordered another 17,000 U.S. soldiers to the war-ravaged country.
The so-called "northern corridor" for U.S. transshipments to Afghanistan includes Russia, Kazakhstan and Uzbekistan.
The first trainload of non-lethal supplies for the U.S. military in Afghanistan left a cargo terminal at the Latvian port of Riga on February 19 and has reportedly crossed Russia and Kazakhstan.
U.S. officials earlier said 20 to 30 trainloads a week could go from Latvia to Afghanistan if the
route is a success.
Russia and NATO signed a framework agreement on the transit of non-military cargos in April 2008, and a subsequent Russia-U.S. deal was signed in January.