A senior Pentagon official said on Tuesday she had no information to corroborate reports suggesting Russia might be moving tactical nuclear weapons by rail, and added the U.S. military had not seen anything to change its own nuclear posture.
"I don't have anything else but the open source reports," said Laura Cooper, a deputy assistant secretary of defense focusing on Russia and Ukraine.
The Pentagon closely monitors Russia's nuclear forces, a core part of its mission since the Cold War.
(Reporting by Phil Stewart and Kanishka Singh)
