Four suspected gunmen behind the deadliest attack in Russia in 20 years are Tajik citizens
"The leaders discussed the increasingly dangerous situation in Syria, and underscored the importance of continued P5+1 unity in ongoing negotiations to prevent Iran from acquiring a nuclear weapon," the White House said.
Obama also told Putin that Russia needs to live to up to the terms of a ceasefire deal with Ukraine, "including the removal of all Russian troops and equipment from Ukrainian territory," the White House said.