There would be consequences for Russia whether it uses a so-called "dirty bomb" or a conventional nuclear weapon, U.S. State Department spokesperson Ned Price said on Monday.
Washington and other Western countries have accused Russia of plotting to use a threat of a device laced with nuclear material as a pretext for escalation in Ukraine.
Asked if Washington would treat the use of a "dirty bomb" the same as any other nuclear bomb, Price said "there would be consequences" for Russia either way.
"Whether it uses a 'dirty bomb' or a nuclear bomb. We've been very clear about that," Price told reporters.
(Reporting by Humeyra Pamuk and Simon Lewis)