WASHINGTON, April 18 - U.S. President Barak Obama called Russian President Vladimir Putin Monday morning for what the White House said was an "intense" conversation about the breakdown of the cease-fire in Syria, USA Today reported.

White House Press Secretary Josh Earnest said the purpose of the call was to "make the case to President Putin that he should use his influence with the Assad regime to live up to the commitments that they've made in the context of the cessation of hostilities."