By Evan Perez and Jim Sciutto
The U.S. government has warned airlines to pay particular attention to the possibility of terrorists attempting to hide explosives in shoes, a result of new intelligence, according to two people familiar with the situation.
The officials stressed there is no specific threat or known plot.
Intelligence collected by the United States and other countries has indicated terror groups have been working on new shoe-bomb designs, the sources said Wednesday.
That knowledge prompted the Department of Homeland Security to warn airlines to be on the lookout for possible explosives hidden in shoes on flights from overseas to the United States, they said.
FULL STORYBy Elise Labott
As the United States puts the finishing touches on possible sanctions against Ukraine, senior Obama administration officials tell CNN they are bracing for the government to intensify its crackdown against anti-government protestors under pressure from Russia.
The officials describe an escalating situation on the ground with both Ukraine and Russia branding the protestors as terrorists. That would suggest the Ukrainian government is planning to impose a state of emergency, giving the military extraordinary powers to further the crackdown.
"Things have gotten very bad," one official said. "The government is speaking in very nasty, aggressive and confrontational terms. It signals they are prepared to do something."
The officials said there was progress over the past week for a political solution, but things soured in recent days since President Viktor Yanukovych met with President Vladimir Putin in Sochi.
FULL POST
A senior administration official told CNN that Secretary of State John Kerry will raise the specter of sanctions on the Ukrainian government in remarks in Paris within the next couple hours.
The official said Kerry will reiterate Vice President Joe Biden's message to Ukrainian President Viktor Yanukovych that his government must protect its people and that Kiev can either choose dialogue and compromise or violence and mayhem.
The official said the U.S. is closely coordinating its response with allies and friends, including the very real potential of sanctions.