1.   In August, Chechnya-based Islamic militants twice invaded the neighboring Russian region of Dagestan.

2.   Russia began the air raids after Islamic militants invaded neighboring Dagestan in August and September.

3.   But Russia sent troops into the territory again last September, after Chechnya-based militants invaded the neighboring region of Dagestan.

4.   Chechnya-based militants invaded villages in Dagestan in August, which helped prompt Russia to send troops into Chechnya in September.

5.   Russia again sent troops into the territory in September, after Chechnya-based militants invaded the neighboring region of Dagestan.

6.   Russia began its raids on Chechnya after Muslim militants invaded neighboring Dagestan in August and September, seeking to create an Islamic state in southern Russia.

7.   Russia sent troops into Chechnya in September, after Chechnya-based Islamic militants invaded Dagestan.

8.   Russia entered Chechnya after militants based there invaded the neighboring region of Dagestan.

9.   Russia sent ground troops into Chechnya following weeks of airstrikes, after Chechnya-based Islamic militants invaded Dagestan in August.

10.   Russian troops entered Chechnya in September after Chechen-based militants invaded a neighboring region and were blamed for apartment bombings elsewhere in Russia.