Security at Olympics in Sochi, Russia

Biathletes train in Sochi, Russia. U.S. officials have urged Americans to be vigilant in Russia, but they haven't altered travel guidelines. (Harry How / Getty Images / February 5, 2014)

MOSCOW -- U.S. warnings that terrorists might try to smuggle explosives aboard Russia-bound flights have added to fears of attacks ahead of Friday's opening of the Winter Olympics in Sochi.

The Department of Homeland Security has alerted airlines flying to Russia that they should be on the lookout for toothpaste and cosmetics tubes that might be used to hide explosive substances, Rep. Michael McCaul (R-Texas), chairman of the House Homeland Security Committee, told U.S. news media on Wednesday.

An estimated 40,000 security troops have been stationed around the Olympic venues in Sochi in what Russian President Vladimir Putin has called a "ring of steel" protecting the games being staged just west of the restive Caucasus region of southern Russia.

In Moscow, extra security is visible at airports and hotels, but screening remains sporadic. European and U.S. passengers arriving on a flight from London to Domodedovo airport Wednesday night breezed through metal detectors unhindered even when the alarms were triggered by their bulging luggage.


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The vast majority of foreign travelers to Sochi transit through Moscow as only two European flights, from Turkey and Germany, offer direct service to the Olympic venue.

Meanwhile, Russian news media reported that a key suspect in the twin suicide bombings in Volgograd in late December had been shot and killed by security forces in the Dagestani town of Izberbash. Dzhamaldin Mirzayev, 30, was suspected of training the two suicide bombers whose attacks on the Volgograd train station and commuter tram killed 34 people, said Rusel Temirbekov, a spokesman for the Russian Investigative Committee, the rough equivalent of the FBI, according to the Itar-Tass news agency.

Chechens, Dagestanis and other Islamic communities that have chafed under Russian domination of the North Caucasus region for centuries have been agitating for an autonomous state in the mountainous area between the Caspian and Black seas. 

Chechen warlord Doku Umarov vowed last summer to disrupt the Olympics to embarrass Putin, who has made the $50-billion-plus investment in the Sochi games a cornerstone of his efforts to project the image of a powerful new Russia.

Although U.S. officials have urged Americans to be vigilant if traveling to Russia, they haven't altered travel guidelines.

"If we should receive information in the coming days and weeks that changes our assessment of whether people should travel to Sochi, we will make that information public," National Security Council spokeswoman Laura Magnuson said.

Secretary of State John F. Kerry also declined to discourage travel to the Feb. 7-23 Olympics.

"I believe that anybody who wants to go to the Olympics, which is just a great event, should go," he told CNN.

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carol.williams@latimes.com

Twitter: @cjwilliamslat