Russian President Vladimir Putin has officially signed a strategic 20-year partnership agreement with Iran, solidifying deepened cooperation in trade, security, and investment. The deal, previously signed in January, comes into effect amid U.S.-Iran nuclear negotiations and growing Western sanctions on both Moscow and Tehran. The agreement is seen as a geopolitical challenge for the U.S. and Israel, as Iran gains leverage with Russian backing. The next round of U.S.-Iran nuclear talks is set to take place in Muscat, Oman.