The bloody ethnic clashes occurring in southern Kyrgyzstan are the worst violence in the Fergana Valley, the heart of Central Asia, since 1990, when hundreds died in another outpouring of mutual hatred. The tragedy is that the current conflict, which risks turning the country into a failed state and tipping the entire region into chaos, could have been avoided.

The latest outburst started with a bar fight between young male Uzbeks and Kyrgyzs in Osh, a city in South Kyrgyzstan, last Thursday. It has since escalated into a series of ethnic pogroms, lootings and burnings. Currently 120 people have been reported killed, with some 1,500 wounded and more than 75,000 refugees—primarily Uzbek women and children—fleeing into Uzbekistan. The Red Cross says that when the dust settles, the dead may number more than 700, once the people now buried in mass graves are counted. Uzbekistan reportedly closed its border to the refugees, and a humanitarian disaster is looming.

The Kyrgyz provisional government is in panic mode. Over the weekend, the authorities called up the army reserves and "volunteers" and shipped them to Osh and Jalal-Abad to quell the unrest. These forces, however, are more a mob than badly needed police SWAT teams. According to Kyrgyz officials, interim President Roza Otunbayeva asked the United States for troops and rubber bullets Friday, but the White House refused. She called Moscow for help next, begging for a military intervention. Was that Mr. Obama's famous "reset button" at work?

This is yet another example of how Kyrgyzstan received little support or attention from the Obama administration—both under the corrupt regime of Kurmanbek Bakiyev, who was toppled last April, and now under "reformist" but pro-Russia Ms. Otunbayeva. Many people in the region allege the fighting was organized by people close to Mr. Bakiyev, who denied his involvement in a press conference in Minsk, where he is living in exile. Regardless of who starting the fighting, Ms. Otunbayeva's agenda, such as a constitutional referendum scheduled for June 27, is in jeopardy.

The Russians so far have refused to send troops. A senior Russian official told me in April that Moscow prefers to keep troops at home, in case it needs them in the volatile Northern Caucasus, where an irregular war against Islamist extremists is ongoing.

Russia did, however, call a Monday meeting of its alliance, the Collective Security Treaty Organization, a group of former Soviet states that includes Armenia, Belarus, Kazakhstan, Kyrgyzstan, Uzbekistan and Tajikistan. So far, the CSTO has decided to "consider all options" and "prepare contingencies" for the leaders. Meanwhile a battalion of Spetnaz commandos was dispatched to the Russian air base in Kant in Northern Kyrgyzstan.

The ability of CSTO to step in is limited. Russia's allies do not have significant battle-worthy forces to spare. Meanwhile, Kazakh President Nursultan Nazarbayev, who has some troops, will have to tread on eggshells, as his relations with Islam Karimov, the Uzbek leader, are strained.

If Russia intervenes, the balance of power in the heart of Eurasia will shift against U.S. (and Chinese) interests. Russia will need to use overwhelming force to quell the violence. Its soldiers are likely to stay there for the foreseeable future, holding the U.S. logistics and air supply base in Manas, which supplies the troops in Afghanistan, hostage. Were Russia to succeed, the interim Kyrgyz government will owe Moscow its political survival. If the Kremlin wants, it will be able to tell the Kyrgyzs to kick the Americans out—and they'll have to comply. Russian envoy Gen. Vladimir Rushailo reportedly is already delivering this message to the Kyrgyz leadership.

If Moscow fails in its mission, ethnic Russians in the north of Kyrgyzstan may come under further attacks. Armed hoodlums already pillaged their property in April. Kyrgyzs are wary of a Russian intervention, remembering their country's status as an "Autonomous Soviet Socialist Republic" of the Russian Federation until 1936, and then a member of the Soviet Union.

This isn't just a threat confined to Central Asia. If Kyrgyzstan is allowed to descend into civil war, radical Islamists, such as Hizb ut-Tahrir (Army of Liberation) and Islamic Movement of Turkestan, affiliated with al Qaeda, likely will expand their propaganda and terror activities. Drug dealers have turned the south of Kyrgyzstan into an important transit-and-production territory. Osh and Jalal-Abad are the transshipping nodes for the Afghan heroin export routes. From there, the drugs pour into Kazakhstan and Russia, and then Western Europe. More chaos means easier drug shipments.

China is the unknown variable in this strategic equation. Beijing views Kyrgyzstan and Central Asia, more broadly, as literally a gold mine of raw materials, hydroelectric energy, and a transit point for pouring its goods into Central Asia and points west. But China is unlikely to intervene at this point without Russia's consent, as Kyrgyzstan is not only outside its borders but also outside its sphere of influence.

The Kyrgyz crisis also demonstrates the limits of power of the European Union and the United Nations. The statements of concern by U.N. Secretary General Ban Ki-moon and EU Foreign Minister Catherine Ashton failed to impress the marauding gangs. Machine guns, rubber bullets and tear gas, eventually supporting a new strong government, may be much more effective in calming the violence.

Washington should resist a Russian or CSTO-flagged "peace-making" operation. Instead, the Organization for Security and Cooperation in Europe, which includes the U.S., Canada and 54 members from Europe and Eurasia should take command. The Obama administration is calling for a U.N.-led force. Regardless, the U.S. should not recognize a Russian "exclusive sphere of interests" in the former Soviet area.

The Obama administration should also focus on ensuring the survival of the Manas air base, which is crucial for aerial refueling over Afghanistan and other logistical operations. Washington should warn the temporary government, which already shut Manas once in June, to stop interfering with the U.S. war effort in Afghanistan amid the planned surge this summer.

If Kyrgyzstan does not calm down soon, the Pentagon might look for alternative bases to Manas, from Tajikistan and Uzbekistan to Turkmenistan and Azerbaijan. Such a relocation will deny scarce revenue to the Kyrgyz people and will leave them in the hands of the Russians—hardly an outcome Ms. Otunbayeva's hapless reformers in Bishkek desire.

Mr. Cohen is a senior research fellow at the Heritage Foundation.