PRAGUE (Reuters) - A senior U.S. State Department official played down on Thursday an announcement by Russia that it will add more than 40 new intercontinental ballistic missiles to its nuclear arsenal this year.
"Those kinds of announcements when made publicly like that obviously have a rattling effect," Victoria Nuland, U.S. Assistant Secretary of State for European affairs, told reporters on a visit to the Czech capital.
"When we look at what is actually happening inside Russia it is far less dramatic," she said.
Putin made his comments a day after Russian officials denounced a U.S. plan to station tanks and heavy weapons in NATO member states on Russia's border. Putin said it was the most aggressive act by Washington since the Cold War.
U.S. Secretary of State John Kerry expressed concern, saying no one wanted to see backsliding "to a kind of a Cold War status."
Nuland, when asked on Russian plans, said Moscow was modernising some existing missiles and that it should stick to limits set in arms control agreements.
"We fully expect and will insist that Russia keep its commitments under the arms control agreements that we have and that all of this will be within that system of verification," Nuland said.
"We will be watching extremely closely what happens."
Washington and Moscow are bound by the 2010 Strategic Arms Reduction Treaty (START) that caps deployed strategic nuclear warheads at 1,550 each and limits the numbers of strategic nuclear missile launchers to 800 by 2018.
Relations between Russia and Western powers have come under strain over Moscow's role in the crisis in Ukraine's east, where fighting between pro-Russian rebels and government forces flared more than a year ago.
When asked about U.S. plans to station tanks and heavy weapons in NATO states on Russia's border, Nuland said options were being considered to make NATO allies "feel safe".
"We are looking at what makes sense there in terms of cost but most importantly in terms of maintaining a very, very strong deterrent," Nuland said.
Reporting by Jan Lopatka; Writing by Jason Hovet; Editing by Robin Pomeroy