WASHINGTON (Sputnik) — Moscow could finalize a deal to deliver S-300 missile defense systems to Tehran as early as this week, Iranian officials said earlier on Tuesday.
"We continue to have concerns about the transfer of the S-300," Kirby said.
The spokesperson went on, "The transfer of this defensive system to Iran is not prohibited under UN security council resolutions."
Russian has been helpful in negotiations with Iran, Kirby added, but the US objects to sending surface-to-air missiles to a regime in Tehran that "continues to conduct nefarious activities," including supporting terrorism across the Middle East.
In April, Russian President Vladimir Putin lifted the ban on S-300 deliveries shortly after the P5+1 group of international negotiators and Iran reached a framework nuclear agreement.