Editor's note: This article was updated to reflect that the visit will reportedly take place on Sept. 11.
U.S. Secretary of State Antony Blinken and U.K. Foreign Secretary David Lammy are to visit Ukraine on a joint visit this week, the two announced on Sept. 10.
"I can confirm that Tony and I will be traveling to Kyiv this week, the first joint visit of this kind for well over a decade," Lammy said during a joint press conference with Blinken.
According to the Washington Post, the visit will take place on Sept. 11.
The U.S. top diplomat arrived in the U.K. for a two-day visit on Sept. 9 to discuss the situation in Ukraine and the Middle East.
Speaking at a press conference in London, Blinken and Lammy said they are "completely aligned on the need to tackle Iran's malign activity in the region and beyond."
Recent media reports said that Iran has supplied Russia with hundreds of ballistic missiles in a boost to its forces waging war against Ukraine. Blinken confirmed the reports during his U.K. visit, threatening further sanctions against Tehran over the shipments.
"We've warned Tehran publicly, we've warned Tehran privately, that taking this step would be a dangerous escalation," Blinken said. "Russia has now received shipments of these missiles."
Washington's confirmation comes a day after EU spokesperson Peter Stano said that Brussels has "credible" information that the shipments took place.
Iran denied delivering ballistic missiles to Russia, calling reports to the contrary "psychological warfare." The Kremlin gave an evasive answer when asked about the reports, saying that Iran and Russia cooperate in "all possible areas."
Russia and Iran have deepened their military and political cooperation since the start of the full-scale invasion of Ukraine in February 2022, and Tehran has provided Moscow with thousands of Shahed kamikaze drones used in attacks against Ukraine.
The Iranian government is also backing a number of militant groups in the Middle East that have carried out attacks against U.S. allies in the region, such as Israel. Washington has repeatedly accused Tehran of destabilizing the security situation in the Middle East.