WASHINGTON (AP) — The White House is promising to unveil new sanctions on Iran in the coming days in retaliation for its arms sales that have bolstered Russia’s invasion of Ukraine, and threatening a “swift” and “severe” response if Tehran moves forward with selling ballistic missiles to Moscow.

National Security Council spokesman John Kirby said Thursday that the U.S. will be “imposing additional sanctions on Iran in the coming days” for its efforts to supply Russia with drones and other technology for the war against Ukraine. And he issued a new warning to Iran that providing ballistic missiles to Russia for use against Kyiv would be met with even more sanctions and actions at the United Nations.

The U.S. has been warning for months of Russia’s efforts to acquire ballistic missiles from Iran in return for providing Tehran with enhanced military cooperation.

“We have not seen any confirmation that missiles have actually moved from Iran to Russia,” Kirby said, but said that at the same time, “we have no reason to believe that they will not follow through.”

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He said that if Iran moves forward, “I can assure you that the response from the international community will be swift and it will be severe.” He said the U.S. would take the matter to the UN Security Council, where Russia has a veto.

“We will implement additional sanctions against Iran and we will coordinate further response options with our allies and partners in Europe and elsewhere,” Kirby said.

Kirby added: “We have demonstrated our ability to take action in response to the military partnership between Russia and Iran in the past. We will do so in the future. In response to Iran’s ongoing support for Russia’s brutal war. We will be imposing additional sanctions on Iran in the coming days. And we are prepared to go further if Iran sells ballistic missiles to Russia.”

The U.S. is set to announce a new set of sanctions Friday against Russia that is timed for Saturday’s second anniversary of the Ukraine invasion and the death last week of outspoken Kremlin critic Alexei Navalny in a Russian penal colony.