Washington, Rabi'II 28, 1435, Feb 28, 2014, SPA -- The United States on Friday warned Russia not to intervene militarily in Ukraine, dpa reported. "Intervention would be a grave mistake," said White House spokesman Jay Carney. He said the US is watching closely to see "whether or not Russia is doing anything that might be crossing the line in any way." Reports about a possible Russian intervention in Crimea have caused "deep concern" in the US and do not comport with Russia's stated intentions to respect Ukraine's territorial integrity, he said. He said US Secretary of State John Kerry related those concerns to Russian Foreign Minister Sergei Lavrov in a phone call earlier Friday. It is their fourth phone call in the last six days. -- SPA 22:29 LOCAL TIME 19:29 GMT www.spa.gov.sa/1204267