Wanted: a large airport in Central Asia, preferably a former Soviet air base. With the clock ticking for the United States to close Manas Air Base in Bishkek, Kyrgyzstan, the Pentagon is scrambling to find an alternative.

The aircraft deployed by the U.S. Air Force at Manas are primarily military cargo planes, aerial tankers for in-flight refueling and smaller aircraft to ferry supplies to troops on combat missions.

The Boeing (formerly McDonnell-Douglas) F-15E Strike Eagle provides close air support for the troops. It flies out of Bagram Air Base inside Afghanistan. The Boeing (formerly McDonnell-Douglas) F-18 Hornet, a carrier-based multirole fighter jet, is capable of hitting aerial and ground targets. It carries out missions of reconnaissance, air escort and defense, close air support and interdiction.

However, Manas' long runway is perfect for the large military transport aircraft Boeing (formerly McDonnell-Douglas) C-17 Globemaster, designed for rapid airlift of troops and cargoes as well as emergency medical evacuation and airdrop missions to and from the military bases or battle sites around the globe. Later, the U.S. Air Force added the aerial refueling tanker aircraft Boeing KC-135 Stratotanker to the Manas contingent.

On Feb. 3 Kyrgyzstan announced it would close Manas for NATO operations. The base has provided key logistical support to NATO's Operation Enduring Freedom in Afghanistan since 2001, when Kyrgyzstan granted the coalition forces unrestricted overflight rights for humanitarian, combat and rescue missions.

Some 1,200 military personnel, mainly Americans, are stationed in Manas. Moreover, the base would have been a vital hub to implement the planned 30,000-troop increase of deployed forces under U.S. President Barack Obama's plan to expand operations in Afghanistan.

Likely to lose Manas, Washington is seeking alternative options for the northern transit route. The United States is negotiating with Uzbekistan and Kazakhstan to secure access to their railway networks for shipping supplies to Afghanistan. Tajikistan opened its airspace and territory for the transit of commercial and humanitarian cargo. Yet it is rather challenging to deliver large volumes of cargo to Tajikistan itself, which is lacking military infrastructure and is dependent on Russia for security support and economic aid.

Turkmenistan, with a large air base in Mary (also known as Merv) only 24 miles from the Iranian border, is another interesting option. But the country is traditionally neutral, and the Iranians may blow a stack if a massive U.S. Air Force presence appears on their doorstep. However, if the Obama administration's outreach to Iran succeeds, that may change.

The United States may be able to return to the airports of Karshi-Khanabad, Uzbekistan. It was evicted from there in 2005 under combined Russo-Chinese pressure and a successful influence operation targeting Uzbek President Islam Karimov. Some equipment also could be moved from Manas to Almaty, Kazakhstan. The United States could also use it for emergency landing. However, the states have not offered to host NATO on any permanent basis, and Almaty is considered too far.

Washington may also try to renegotiate Manas, but this will depend on Russia's goodwill. The Pentagon also has the very expensive option of supplying the troops by air from Qatar and Kuwait, where the United States has air bases, but be as it may, the Manas eviction note puts the "Northern supply route" for Afghanistan in jeopardy, thanks to Russia's hard-nosed practice of geopolitical arts.

Ariel Cohen is senior research fellow in Russian and Eurasian studies at the Heritage Foundation.