U.S. backs plan to keep Russia at bay

(CNN) - On the same day that 70 international investigators reached the crash site of Malaysia Airlines Flight 17 - the largest group yet - President Obama and Russian President Vladimir Putin had a phone conversation about the country where the wreckage and bodies lie: Ukraine.

The White House says the President told Putin he was deeply concerned about "Russia's increased support for the separatists in Ukraine."  Those are the very rebels who are suspected of shooting down flight 17, and keeping investigators off the site for days on end.

Now that Putin has been accused of sticking his mitts far into Ukraine, CNN's Barbara Starr reports on a plan to slap them back before they creep farther west.