moscow subway explosion - Neither he nor Putin, who was on official trip in Siberia, announced concrete and it was unclear whether Russia has new strategies to unleash in the Caucasus, where separatist violence has spread from Chechnya to neighboring republics.

Although the Russian army battered Chechen rebels in the massive assaults a decade ago, the separatists continue to move through the mountains of the region and forests with relative ease and launch small frequent attacks.

Transit system in New York has improved security as a precautionary measure after the attacks in Moscow. A spokesman for the Metropolitan Transportation Authority, Kevin Ortiz, said the agency has a "security presence" but declined further comment.

The agency is in charge of buses and subways of New York and suburban railways, and bridges and tunnels.

The blasts in Moscow virtually paralyzed the movement in the center as emergency vehicles rushed to the stations.

Park Kultury in the explosion, the suicide bomber wearing a belt packed with plastic explosive and placed outside the train doors opened, said Vladimir Markin, a spokesman for Russian research organization higher. The woman was not identified, told reporters.

A woman who sells newspapers outside the Lubyanka station, Ludmila Famokatova, said there seemed to be panic, but that many of the people leaving were shocked.

"A man was crying, the cross, saying" thank God I survived, "he said.