A new classified intelligence assessment concludes it is more likely than previously thought that Russian forces will enter eastern Ukraine, CNN has learned.
Two administration officials described the assessment but declined to be identified due to the sensitive nature of the information.
The officials emphasized that nothing is certain, but there have been several worrying signs in the past three to four days.
“This has shifted our thinking that the likelihood of a further Russian incursion is more probable than it was previously thought to be,” one official said.
The buildup is seen to be reminiscent of Moscow’s military moves before it went into Chechnya and Georgia in both numbers of units and their capabilities.
U.S. military and intelligence officials have briefed Congress on the assessment.
The focus of the investigation into missing Malaysian Airlines Flight 370 is now on the captain and co-pilot of the plane.
A U.S. official tells CNN that the FBI has now has access to the captain and co-pilots hard drives, including the drive from the captain's flight simulator and results are expected to be handed over to Malaysian officials in a day or two.
An official involved in the investigation tells USA Today that the pilot is, in the paper's words, "believed to be solely responsible for the flight being taken hundreds of miles off course."
That official says it was not an accident.
Crews are also resuming the search for the plane in the southern Indian Ocean.
New satellite images provided by a French defense firm show 122 objects floating not far from other satellite sightings of possible debris.
The objects range from about 3 feet to about 75 feet in length, scattered over an area the size of Denver.
The images were taken Sunday, but a search of the area has produced nothing so far.
Unrelated to the satellite images, three objects were spotted Wednesday by two aircraft, but searchers were unable to relocate the objects on subsequent passes.
OutFront: William Dermody, World News Editor for USA Today. Along with our Richard Quest, CNN aviation analyst Miles O'brien, and John Nance is an Aviation Analyst for ABC's "World News".
"It was very frightening. I was fearful for him when we saw him going back and forth on the ledge initially."
A woman watching from a nearby building captured terrifying video of a Houston construction worker trying to escape from a building engulfed in flames.
Karen Jones is the woman who captured the rescue on her cell phone and she's OutFront.
In an interview with CNN's Erin Burnett, former President Jimmy Carter talks about his letter to Pope Francis. In it, Carter called on the pontiff to support efforts to stop abuse against women.
"I asked him to join with me in doing some of these things to prevent slavery, and to prevent killings, and to prevent unnecessary prostitution, and to prevent things of that kind," Carter said.
The former president also said he didn't ask the Pope to change the Catholic Church's policy on female priest, which he supports.
"[The Pope] said the role of women within the Catholic Church should be enhanced in the future," Carter said.
Much of the coverage of Malaysia Airlines Flight 370 has focused on the passengers and the pilots but there were other people on the plane when it vanished.
The teenage daughter of the flight's chief steward has been tweeting to father ever since the plane disappeared.
Come home fast, dad.. It's the only thing I want... :') pic.twitter.com/yc6Ypie6Ed
— . (@Gorgxous_) March 8, 2014
Jeanne Moos has the story.