Development enables resumption of talks that were stalled after Moscow demanded assurances sanctions over Ukraine won't impact its ties with Tehran

Hossein Amir-Abdollahian to depart Tuesday as negotiations on revised accord stall over Kremlin's insistence that Ukraine sanctions not hinder its trade with Tehran

Iranian top diplomat accuses US of making new demands for nuclear talks and complicating negotiations in Vienna

Moscow demanding guarantees Western sanctions won't affect trade with Iran; US says it won't play 'Let's Make a Deal' with Moscow, as Iran accuses Washington of holding up talks

White House dismisses possibility Russia sanctions will hinder talks in Vienna, saying both Washington and Moscow share common goal of preventing Tehran from obtaining nukes

Following Moscow's insistence that sanctions over Ukraine not harm its cooperation with Islamic Republic, Tehran says it won't allow 'external factor to affect national interests'

Degree of Putin's frustration with US opposition to his incursion will dictate whether he prioritizes deal to prevent nuclearized neighbor over effort to push back against the West

But after blaming West, Tehran too urges political solution to burgeoning conflict

Tehran, itself under US sanctions, makes statement as Washington, Brussels set to announce economic measures against Russia

Maneuvers reflect bold attempt by Kremlin to halt decades of NATO expansion after the end of the Cold War; Putin working to strengthen alliances with countries opposed to West