Russian state-run media have broadcast a video showing President Vladimir Putin aboard a nuclear-capable strategic bomber, in an apparent effort to showcase the country's military might.

The footage shows Putin boarding a Tu-160M in the central Russian republic of Tatarstan on Thursday. It shows him clutching the control stick while the plane is in flight.

Experts say the aircraft is being used to launch missile attacks on Ukraine. Putin made his flight two days before the second anniversary of the start of Russia's invasion.

Russian media also reported on an interview with former President Dmitry Medvedev, now deputy chair of the security council.

Medvedev said Russian forces will have to march again on Kyiv, as the Ukrainian capital poses an international threat to Russia's existence.

He also said Ukraine has a choice between endless war and life in a common state with Russia.

Meanwhile, Reuters news agency quoted six sources on Wednesday as saying Iran had supplied Russia with numerous surface-to-surface ballistic missiles.

It cited three Iranian sources as saying many of the missiles are of a type that can hit targets up to 700 kilometers away.

Reuters said one source revealed that the shipments started early last month. It cited an Iranian military official as saying there would be more shipments in the coming weeks.

On Thursday, Ukrainian President Volodymyr Zelenskyy posted a comment on social media referring to the city of Avdiivka in the eastern region of Donetsk. Russian forces took control of the strategically important city earlier this month.

Zelenskyy stressed his intention to reinforce defenses near the city to prevent further Russian advances. He said his people had made a detailed examination of the situation in Avdiivka and to the south.

Zelenskyy disputed Moscow's claim that Russia had regained control of the village of Krynky on the east side of the Dnipro River in the southern region of Kherson. He said Ukrainian marines were holding a bridgehead there.