The United Kingdom has introduced fresh sanctions against Iran for supplying ballistic missiles and other weaponry to Russia, further escalating tensions over Tehran’s role in the war on Ukraine.

The British Foreign Office announced Monday that it will freeze the assets of Iran’s national airline, Iran Air, and its state-owned shipping company, both accused of facilitating the transfer of weapons. Additionally, the sanctions target the Russian cargo ship Port Olya-3, which was reportedly involved in delivering the missiles from Iran to Russia.

“Iran’s actions threaten global security and cannot be tolerated,” said Foreign Secretary David Lammy ahead of his statement at the United Nations Security Council. “We have been clear—any transfer of ballistic missiles from Iran to Russia would trigger a strong response.”

The move coincides with the 1,000th day of Russia’s full-scale invasion of Ukraine and comes just a day after U.S. President Joe Biden authorized Kyiv to use American-supplied missiles to strike deeper into Russian territory.

Speaking at the G20 summit in Brazil, UK Prime Minister Keir Starmer reinforced Britain’s commitment to Ukraine, stating that support must continue for as long as needed. “We need to double down,” he emphasized.

The asset freezes will restrict Iran Air from operating direct flights to and from the UK and will prohibit British businesses and individuals from engaging in financial transactions with the sanctioned entities.

This latest round of measures follows similar sanctions imposed in September in coordination with Germany and France, further tightening pressure on both Iran and Russia.