US Secretary of State John Kerry has called Russian Foreign Minister Sergei Lavrov to express American concerns about the targets the Russian fighter jets have been striking in Syria.

In a telephone call with Lavrov on Thursday, Kerry accused Moscow of launching airstrikes against targets in Syria were not related to the Daesh (ISIL) terrorist group, State Department spokesman John Kirby said.

"The secretary repeated our concerns about the preponderance of targets that are being struck by Russian military forces that are not ISIL-related," Kirby said.

A new US intelligence assessment has found Russia has targeted militant groups backed by the Central Intelligence Agency (CIA) in Syria.

The assessment, shared by commanders on the ground, has led American officials to conclude that Russian warplanes have intentionally struck CIA-backed militants in a string of attacks running for days, the Wall Street Journalreported.

Kirby said that there were "no tactical level decisions" made during the 30-minute telephonic conversation between Kerry and Lavrov.

On Wednesday, Russia fired 26 long-range cruise missiles from its warships in the Caspian Sea against Daesh (ISIL) positions in Syria. Three unnamed US military officials claimed on Thursday that some of the cruise missiles landed in Iran.

The State Department spokesman said he could not confirm these reports. “I can’t confirm it but I think it points all the more towards the need to have proper deconfliction procedures in place,” Kirby said, using a military term, deconfliction, which means rival armies will talk to one another in order to avoid accidental encounters between their forces.

Last month, the United States and Russia renewed high-level military contacts to discuss mechanisms in order to avoid accidental encounters between their forces in Syria.

US Secretary of Defense Ash Carter and his Russian counterpart Sergei Shoigu spoke by telephone on September 18, according to Pentagon spokesman Peter Cook.

"The secretary and the minister talked about areas where the United States and Russia's perspectives overlap and areas of divergence," Cook said. "They agreed to further discuss mechanisms for deconfliction in Syria and the counter-ISIL campaign.”

The United States and Russia broke off direct military contacts in April 2014 over a dispute over the crisis in Ukraine.