Russia's President Dmitry Medvedev called US President Barack Obama on Tuesday and the two leaders discussed the worsening situation in Georgia and tensions over ex-Soviet states, the White House said.
The call came as Georgia warned of the risk of a new war with Russia and Moscow raised the battle-readiness of its forces, ahead of the anniversary of their conflict over rebel South Ossetia.
"Russian President Medvedev called President Obama today to wish him happy birthday," the White House said in a press statement.
"During the call, the presidents discussed the situation in Georgia and the need to decrease tensions in the region.
"President Obama reiterated the importance of working through established crisis management mechanisms such as the Joint Incident Prevention and Response Mechanism and underscored the need for international monitors."
Obama was celebrating his 48th birthday on Tuesday.