Russian presidential aide and Security Council secretary Nikolai Patrushev is visiting Iran, possibly to discuss buying Iranian missiles. Russian forces are reportedly facing a serious shortage of weapons in Ukraine.

Russia's state-run media reported on Wednesday that Patrushev was scheduled to meet officials including the secretary of Iran's Supreme National Security Council, Ali Shamkhani, who oversees the country's defense and foreign policies.

The Institute for the Study of War, a US think tank, said on Tuesday that Patrushev is likely to discuss a potential sale of Iranian ballistic missiles to Russia.

Iran recently acknowledged that it has provided drones to Russia.

Observers say Moscow may be trying to rebuild its military with weapons from Iran.

Ukrainian President Volodymyr Zelenskyy said in a video released on Tuesday that the situation is especially tough in the eastern region of Donetsk, with dozens of attacks by Russian forces every day.

He vowed an all-out effort to defend the country, saying Ukrainians will not yield a single centimeter of their land.

On Saturday, the Washington Post quoted US government sources as saying the Biden administration is privately encouraging Ukraine to signal openness to negotiations with Russia.

The US newspaper says the move is aimed at maintaining the support of other countries as they are getting wary of fueling a war for many years to come.