Russia is building up its troop presence on the border with Ukraine.
Russian forces in the area now total 30,000 troops - up from 20,000 from Monday. President Obama warned Russia's president Vladimir Putin on Tuesday that he would face "additional costs" if Russia does move further into Ukraine.
Obama defends handling of Ukraine crisis
CNN's Erin Burnett spoke with Former President Jimmy Carter and asked him whether there was a way to stop Russia at this point, short of war.
"I think we have to be very bold and strong in preventing Putin from having a temptation to move militarily into Eastern Ukraine," Carter said.
What if the passengers of Flight 370 tried to send messages before the plane went missing?
That's a crucial question not only for family members of the passengers, but for investigators who want to know what happened in the flight's final moments.
If and when the plane is found, forensic experts say personal cell phones and electronics may be the key to solving one of the biggest aviation mysteries in history.
Our Ted Rowlands is Outfront with the story.
Search planes continue to scour the possible debris site for Malaysia Airlines Flight 370. It's a remote area about 1,500 miles southwest off Australia's west coast.
Locating the debris is just the first step in solving this aviation mystery. Crews must find the bulk of the wreckage, which could be miles deep in the sea.
One crucial tool to finding that wreckage is an autonomous underwater vehicle.
CNN's Rosa Flores has the report OutFront.
How a probe like this could help find #mh370 coming up on @OutFrontCNN on @cnn At 7pm ET pic.twitter.com/QZxuB8jZlW
— Rosa Flores (@RosaFlores) March 25, 2014
The search for wreckage of Malaysia Airlines Flight 370 resumed Wednesday, with search planes traveling to the suspected crash site 1,500 miles off the Australian coast.
Finding this debris is critical when it comes to determining what went wrong. Was it pilot error?
OutFront has been looking at an incident from 2005 involving a Boeing 777 that raises questions about the training pilots are getting.
According to the Australian Transportation Safety Bureau, the incident happened on a flight from Perth to Kuala Lumpur.
It's said to have been an issue with the auto-pilot.
The takeaway from the report: "When the hardware failure occurred, combined with the software anomaly, the crew were faced with an unexpected situation that had not been foreseen. Subsequently, the crew had not been trained to respond to a specific situation of this type..."
Boeing did not return our request for a comment on the incident.
But if there was some sort of mechanical failure with Flight 370 would the pilots have known what to do?
OutFront: Richard Quest, CNN aviation analyst Miles O'Brien, pilot Arthur Rosenberg and Robert Goyer Editor-in-chief of Flying Magazine.