Presidents Barack Obama and Vladimir Putin have discussed security at the Sochi Winter Olympics, amid rising fears in Washington for the safety of US athletes after terror threats against the Games.
The US and Russian leaders talked about how to ensure a "safe and secure" event next month in the Black Sea resort and nearby mountains, and also discussed Syrian transition talks in Geneva and nuclear diplomacy with Iran, the White House said.
The United States has offered "full co-operation" to Russia on securing the Games, but there have been some complaints by members of Congress that Moscow has held back some intelligence.
The call on Tuesday came amid signs of subtle but rising pressure on Russia from Washington over securing the Games.
On Monday, the Pentagon said it was ready to deploy air and naval forces - including two ships - to help secure the Olympics, which begin on February 7.
US Defence Secretary Chuck Hagel had already offered American support during a January 4 phone call with his Russian counterpart Sergei Shoigu.
Islamist insurgents based in North Caucasus republics such as Dagestan who are seeking their own independent state have vowed to disrupt the Sochi Games in an effort to undermine Putin.
In a new video threat posted on a prominent North Caucasus Islamist website, two men sitting in front of a jihadist flag warn of planned attacks at the event.
The introduction says the men were responsible for two suicide bombings in the southern city of Volgograd last month - Russia's deadliest in three years - which killed 34 people.
Russian security officials are hunting down three potential female suicide bombers, one of whom is believed to be in Sochi.
Police leaflets at a central Sochi hotel on Tuesday contain warnings about three potential suicide bombers.
A police letter says that one of them, Ruzanna Ibragimova, a 22-year-old widow of an Islamic militant, was at large in Sochi.
Russian authorities have blamed the so-called "black widows" of slain insurgents for previous suicide attacks in the country.
Earlier this month, the State Department warned that Americans headed to Sochi should be vigilant to ensure their security.