US President Barack Obama spoke by phone Wednesday with Vladimir Putin, thanking his Russian counterpart for his role in reaching a deal on Iran’s nuclear program.

US President Barack Obama spoke by phone Wednesday with Vladimir Putin, thanking his Russian counterpart for his role in reaching a deal on Iran's nuclear program.

US ties with Russia have been strained to breaking point over the war in Ukraine, but Russia was an "important" part of the group of nations that negotiated the deal with Tehran.

"The president thanked President Putin for Russia's important role in achieving this milestone, the culmination of nearly 20 months of intense negotiations," the White House said in a statement.

"The leaders committed to remain in close coordination" it continued, "and also expressed a desire to work together on reducing regional tensions, particularly in Syria."

There was no mention of the ongoing violence in Ukraine.

Obama has twice in two days offered praise for Russia's role in reaching a deal with Iran.

"Russia was a help on this," he told the New York Times.

Russia was a part of the P5+1 group that signed the nuclear deal with the Islamic Republic on Tuesday.