From NPR News in Washington, I'm Windsor Johnston.While the stand-off in Ukraine continues,the US and other world leaders are continuing to try and de-escalate the crisis.As NPR's Dianna Douglas reports,Secretary of State John Kerry issued a stern warning to Russia today.The State Department says Kerry advised his Russian counterpart against continued military escalation and provocation in Ukraine.Kerry also said that steps by Russia to annex Crimea would close any available space to diplomacy.During a phone call, Kerry urged Russian Foreign Minister Sergei Lavrov to exercise the utmost restraint.Vacationing in Florida, President Obama spoke to the leaders of France, England and Italy, and to the heads of Latvia, Lithuania and Estonia.The White House says all of the leaders reject the planned March 16 succession referendum in Crimea.They call on Russia to pull its forces back to their military bases,and they support the formation of a contact group leading to direct talks between Ukraine and Russia.Dianna Douglas NPR News, Washington.The US Navy has sent a guided-missile destroyer to assist in the search for a missing Malaysia Airlines flight.NPR's Sam Sanders reports that3 Americans were on board the flight which went missing more than 24 hours ago.The Navy has appointed the USS Pinckney to the southern coast of Vietnamto help search for the plane, which had 239 people on board.The Navy has also sent the P-3C Orion aircraft from Japan.
