US bans carry-on liquids on direct flights to Russia
The US government has banned all liquids from carry-on bags on nonstop flights to Russia, on the eve of the Sochi Winter Olympics.
The restrictions come a day after US officials warned that explosives could be smuggled on flights to Russia in toothpaste tubes.
Terrorists could attempt to assemble explosive devices in flight or upon arrival, the officials warned.
Security has been elevated in the lead-up to the Games, which start on Friday.
The US airline restrictions unveiled on Thursday temporarily ban carry-on liquids, gels or aerosols aboard direct flights to Russia.
Russia has already banned all liquids, pastes and gels from its airports and internal flights last month.
On Thursday, US President Barack Obama said Russia had an "enormous stake" in foiling terrorism at the Games.
He told NBC television network the US government was doing everything it could to ensure athletes' safety.
The US has already placed two warships in the Black Sea, ready to offer help in case of a security emergency during the Games.
Deputy Prime Minister Dmitry Kozak has said the level of security at Sochi "is similar to that of any other safe city in the world".
Fears surrounding the Winter Olympics in Russia were heightened following two suicide attacks in Volgograd in December, as well as numerous threats from Islamist militants in the Caucasus region.
Security has not been the only controversy surrounding the build-up to the Games, however.
Russia's controversial laws on homosexuality, passed last year, have provoked international criticism.
UN Secretary General Ban Ki-moon referred to the issue in a keynote speech he gave at a session of the International Olympic Committee in Sochi on Thursday.
"Sport has an amazing power to spontaneously unite people," he said. "We must raise our voices against attacks on lesbian, gay, bisexual, transgender or intersex people.
"We must oppose the arrests, imprisonments and discriminatory restrictions they face."
Mr Ban also renewed his call for all warring parties around the world to observe an "Olympic Truce" and lay down their weapons during the Games.
The Russian foreign ministry made a similar appeal, saying its call was "primarily addressed to the sides of the blood-letting in Syria".