The United States has doubled down on its claim that Iran is planning to sell “hundreds” of drones to Russia to be used in Ukraine, a day after Tehran explicitly rejected the allegation.

Jake Sullivan, the US national security adviser, on Saturday reiterated his statement made earlier this week that Iran wants to sell weapons-capable unmanned aerial vehicles (UAVs) to Moscow.

He released satellite imagery to the US-based CNN network that purportedly showed that a Russian delegation visited an airfield in central Kashan at least twice in the last month.

The Russian delegation is alleged to have been treated to a showcase of the Shahed-191 and Shahed-129 drones, both capable of carrying precision-guided missiles.

Sullivan also claimed earlier this week that Iran is training Russian forces in using the drones, and said it is unclear if any drones have already been sold to Moscow.

Iran’s Foreign Minister Hossein Amirabdollahian has denied the US claims in a phone call with his Ukrainian counterpart Dmytro Kuleba on Friday, saying Iran will not do anything to prolong the fighting.

Amirabdollahian said the claims are aimed at advancing the US’s political goals as they came right before US President Joe Biden began his tour of the Middle East, with a united stance against Iran being a major agenda of the trip.

“The fundamental and explicit stance of the Islamic republic in opposing war and supporting a stop to the war is not based on a double standard like some Western countries,” Amirabdollahian told Kuleba, adding that Iran also opposes the fighting in Afghanistan, Yemen and Palestine.

The developments also come as Russian President Vladimir Putin and his Turkish counterpart Recep Tayyip Erdogan are expected to arrive in Tehran on Tuesday for a trilateral sit-down with Iran’s President Ebrahim Raisi to discuss the Syria crisis.

The leaders are expected to hold bilateral meetings as well, and Putin will reportedly meet with Iran’s Supreme Leader Ali Hosseini Khamenei.

Turkey has supplied Ukraine with its armed Bayraktar drones, which have been used in the war against Russia.

Since the start of the Ukraine war in February, Iran has said it wants the fighting to stop through dialogue, but has refused to condemn Russia, instead blaming NATO’s expansion in Europe as the root cause of the conflict.

US officials had also claimed in March that Russia had turned to China for help in supporting the war in Ukraine. So far, there has been no evidence of Chinese arms being used in Ukraine.

Sullivan also confirmed to reporters in late May that the US has seen no evidence that China has provided any military or economic support to Russia for the invasion.