Intensified Russian cargo flights to Iran are raising fresh concerns in Washington as U.S. pressure mounts during ongoing nuclear negotiations in Geneva. Flight tracking data shows a Russian Ilyushin Il-76 heavy transport aircraft completed four rotations to Tehran within just ten days, carrying undisclosed cargo. The development comes shortly after reports that Iran finalized a €500 million arms agreement with Russia, including 9K333 Verba man-portable air defense systems and 2,500 9M336 missiles to strengthen short-range, low-altitude defenses.