Russia may resume a deal to deliver S-300 surface-to-air defense systems to Iran if only the UN decides to lift its ban on arms sales to Tehran, a leading Russian defense expert said on Friday.

Negotiators from Iran, the United States and other world powers agreed on Thursday to a framework for a final agreement to curb Tehran’s nuclear program.Iran agreed in principle to accept significant restrictions on its nuclear facilities for at least a decade and submit to international inspections. […]