President's 'invincible' weapons: how worried should we be?

Russian President Vladimir Putin has boasted of a new arsenal of weapons that render Western missile defence systems obsolete, in a move that appears to signal the start of a fresh arms race with the US.

What exactly are the weapons?

This included a cruise missile with nuclear propulsion that can travel an unlimited distance and move in an unpredictable pattern -- which Putin said is not owned by any other country and will be able to get around missile defence systems.

He also showed the "Sarmat" -- an intercontinental ballistic missile that will replace Russia's existing rockets and comes with technology to outsmart missile defence.

Among other projects, Russia has developed unmanned underwater devices that move much faster than torpedoes and can carry nuclear warheads, Putin said.

How worried should we be?

Putin used bellicose language as he unveiled the weapons, warning the world to "listen up now", but also insisted the weaponry would only be used in defence of Russia or its allies.

Analysts have pointed out some of the technology is not new, while others have suggested the Kremlin relied on video simulations to demonstrate some capabilities because the weapons are not fully developed.

"We already knew about the 'Sarmat' and we already knew about big complications with the rocket," independent Russian military analyst Alexander Golts told AFP.

"At the end of 2017 it wasn't the rocket itself that was tested, but a mock-up. I suspect we were shown an edited clip: first the mock-up takes off, then another rocket is flying," he said.

In an interview with the American news network NBC, Putin himself later admitted the weapons were in various stages of development, but some are battle ready.

Why is Putin doing this now?

With less than three weeks to go before a presidential election that he is widely expected to win, Putin was appealing to the Russian electorate as well as an international audience.

In the speech he repeatedly referred to the humiliation Russia suffered in the years after the fall of the Soviet Union in 1991 and contrasted the situation then to the country's global standing now.

Putin enjoys sky-high approval ratings because many Russians see him as having restored national pride.

Opposition leader Alexei Navalny said the president focused on the military in his speech because it is the only area "where he can lie with impunity".

If he had boasted of Russia's achievements in education or healthcare, voters would have been able to see the deception themselves, Navalny said in a YouTube video.

Is this the start of a new arms race?

Putin presented Russia's military efforts as a response to recent actions by the US, which last month unveiled plans to revamp its nuclear arsenal and develop new low-yield atomic weapons.

He told NBC an arms race effectively started again when Washington pulled out of the Soviet-era Anti-Ballistic Missile Treaty under George W. Bush.

"In the US, after this speech, the entire political elite will vote for an increase in military spending," political analyst Alexei Makarkin told AFP, adding that Putin's address was a "challenge" to Washington.

Other analysts have said the move marks the start of an arms race, though a Kremlin spokesman denied the suggestion.

What will the impact be?

Putin's speech has further exacerbated tensions with the US, which have hit Cold War-era highs over conflict in Syria and Ukraine as well as accusations Moscow interfered in the US 2016 election.

Washington has accused Moscow of openly breaching Cold War-era treaties, a charge the Kremlin denies.

But while Putin's announcement might boost Russia's clout in the immediate future, military analyst Golts told AFP that getting involved in an arms race could backfire on Moscow.

"The USSR arms race ended badly, it ruined the Soviet economy. And Russia does not have the same resources as the Soviet Union. There is every reason to believe that for Russia it would also end badly."