NATO’s top official said in October he did not believe there would be new deployments of U.S. missiles in Europe and U.S. National Security Advisor John Bolton said Washington was a long way from taking decisions about deploying missiles in Europe.
Ryabkov said Moscow was sceptical about assertions from U.S. and NATO officials that no such new missiles would be deployed.
"We hear (the denials) but nothing more," said Ryabkov. "Plans have been changed many times before. We don't want to be disappointed in our (U.S.) colleagues again and therefore we are assuming the worst case scenario in our military planning."
Ryabkov said he believed the United States would be able to deploy intermediate-range nuclear missiles in Europe "within years," something he said would fuel a dangerous arms race.
"We can't ignore the potential deployment of new American missiles on territory from where they will be a threat to Russia and its allies," the TASS news agency cited him as saying.
"In the event of such a deployment the Americans would gain significant extra capabilities, allowing them to strike at targets deep inside Russia."
Putin has previously said that Russia would be forced to target any European countries that agreed to host U.S. nuclear missiles.
Ryabkov said it was too early to speak about specific military retaliatory steps, but said Moscow's response would be "effective" and "relatively inexpensive."