Russian police have killed a senior Islamist militant in a shoot out in the North Caucasus.
The operation was part of a nationwide tightening of security ahead of next month’s Winter games in Sochi.
On Sunday a militant group from Dagestan posted a video claiming responsibility for last month’s deadly bombings in Volgograd and threatened more of the same at the Olympics.
Russian security forces are now searching for a potential female suicide bomber said already to be in the Black Sea resort.
She has been identified as 22-year-old Ruzanna Ibragimova, nicknamed “Salima”.
Two other so-called ‘black widows’ of slain insurgents are also being sought.
Russian officials have blamed female bombers for previous suicide attacks in the country.
In a spirit of cooperation and as part of its own plan to keep its citizens safe, the US has pledged air and naval support to the Russian government if required.
Washington has also offered counter-bomb technology developed in Afghanistan to thwart roadside explosive devices.
On Tuesday, President Obama phoned President Putin to discuss how best to have a safe and secure Winter Olympics.