The US has offered to assist Russia with security for the Winter Olympics in the wake of the attacks in Volgograd, the White House says, dpa reported.
"The United States stands in solidarity with the Russian people against terrorism," spokeswoman Caitlin Hayden said.
"The US government has offered our full support to the Russian government in security preparations for the Sochi Olympic Games, and we would welcome the opportunity for closer cooperation for the safety of the athletes, spectators, and other participants."
The US condemned the two attacks and offered condolences to the families of the victims, she said.