MOSCOW (Reuters) - The Kremlin told Washington on Wednesday it would act decisively if the United States undertook any new “unfriendly steps” such as imposing sanctions, the RIA news agency reported, citing a foreign ministry source. It said the comments were made by Russian President Vladimir Putin’s foreign policy adviser Yuri Ushakov who invited the U.S. ambassador in Moscow to talks following a phone call on Tuesday between Putin and U.S. President Joe Biden, RIA said.