Backgrounder: Lingering resentment over NATO’s expansion has strained U.S.-Russia relations.

The flow of Russian conventional weapons to Iran—notably sophisticated surface-to-air defense missiles—has increased markedly of late, complicating U.S.-led efforts to tamp Tehran’s nuclear ambitions.

As the world struggles to find a formula for dealing with suspicious nuclear developments in Iran , Russian diplomats have been holding bilateral talks with Iranian officials on a proposal they say c…

Russia has suspended its participation in a treaty on conventional arms and voiced opposition to a missile shield in its backyard. Is a new era of mutual hostility in the making?