Terrorists struck Thursday in the Caucasus region, which has been a hotbed of separatist and Islamist violence, particularly in Chechnya. The Islamists raided police stations and government buildings, including the headquarters of the Interior Ministry and a building used by Russia's Federal Security Service, or spy agency, in the Caucasus city of Nalchik, which is in the predominantly Muslim republic of Kabardino-Balkariya. Terrorists struck after authorities had closed in on some of their operatives in an apartment building. The killers also took hostages at a police station, who were later freed.

Russian President Vladimir Putin ordered all exits from the city blocked and sent in convoys with trucks full of soldiers. More than 100 people, most of them militants, were killed in the attacks and ensuing police responses. Russia's deputy interior minister, Andrei Novikov, said two Islamist radicals with experience in Chechnya, Anzor Astemirov and Ilyas Gorckhanov, had recruited fighters mostly among the local population. Chechen militants claimed responsibility on a Web site for Thursday's and Friday's violence.

As the terrorist insurgency in Chechnya, which is over a decade old, has been increasingly, if brutally, contained, violence has spilled over to neighboring areas. Most memorably, in North Ossetia in the city of Beslan last year, 331 people, half of them children, died in a terrorist seizure of a school.

Apart from the obvious human toll, smaller-scale attacks can have a profound psychological effect and can influence policy-making. Governments can ill afford complacency in the face of the ongoing jihadist threat. Although it is highly unlikely that Chechen militants and those aligned with them would now be able to wrest regions in the Caucasus from the rest of Russia, their violence can make the area difficult to govern and can limit Moscow's authority. The terrorists apparently think that they could improve their negotiating leverage with the Kremlin through their acts of terror.

Rampant corruption has made the area more vulnerable to attack, since terrorists have been able to purchase the aid or indifference of authorities. Also, in Chechnya, soldiers have even been willing to sell weaponry to insurgents. Given those problems with corruption and ineffectual local rule, it is no wonder Mr. Putin has been keen to extend central power in an effort to rein in the Islamist insurgency.

While Mr. Putin should strive to maintain a level of oversight over Russia's far-flung regions, he also needs to allow the people of the Caucasus legitimate political outlets for their grievances. The region is particularly poor, and its prospects are only worsened by the corruption. In Karachayevo-Cherkessiya this year, demonstrators occupied regional government headquarters twice to protest the alleged involvement of the president's former son-in-law in the killing of seven businessmen.

Thursday's attacks also illustrate that, despite their differences, Mr. Putin and Georgian President Mikhail Saakashvili face a common Islamist and separatist threat in the Caucasus. Though Mr. Saakashvilli's earliest priority as president was to establish his country's autonomy from Russia, he has by and large accomplished that feat, and can now afford to coordinate with Moscow in improving security in the region.

The United States and its Western allies should also clearly demonstrate their solidarity with Russia and be prepared to assist with any counterterrorism help. The attacks in Russia serve as yet another reminder of the danger posed by aspiring jihadists in other parts of the world.