UK Foreign Secretary Boris Johnson urged Russia and Iran to influence Syrian President Bashar Assad to allow the humanitarian access to besieged areas, said Tuesday.

“We seek those with influence over the Assad regime, including Russia and Iran, to ensure humanitarian access to the besieged areas in line with UN Security Council resolutions commitments made as members of the International Syria support group,” Johnson said.

He also said that Russia has a unique power to influence Syrian President Bashar Assad to “end the carnage and return to the negotiations table.”