Russia has developed a new cruise missile that is invincible, according to President Vladimir Putin.
Mr. Putin made the revelation as he laid out his key policies for a fourth presidential term, ahead of an election he is expected to win in 17 days' time.
He showcased a range of new weapons, including the cruise missile that could "reach anywhere in the world".
Using video presentations, he said the missile could not be stopped by the US shield in Europe and Asia.
It was "a low-flying, difficult-to-spot cruise missile with a nuclear payload with a practically unlimited range and an unpredictable flight path, which can bypass lines of interception and is invincible in the face of all existing and future systems of both missile defense and air defense".
Another weapon he discussed was a submarine-launched, long-range missile capable of delivering a nuclear warhead.
During the two-hour televised speech to a joint sitting of both houses of parliament, he encouraged Russians to suggest names for the two systems. He argued that Russia had reacted after years of pleading with the US not to break away from anti-missile treaties.
Mr Putin faces seven challengers on 18 March, although none is expected to attract widespread support. The president played no part in a raucous televised debate broadcast on Wednesday that featured the other candidates.
Absent from the campaign is prominent opposition leader Alexei Navalny, who has been barred from running and has called on voters to boycott the poll.
President Putin has so far done little campaigning, and until now said little about his plans for the next six years.
President Putin's emphasis on a strong Russia modernizing its nuclear arsenal is a reflection of similar statements over recent months from his US counterpart Donald Trump.
In his remarks, Mr. Putin highlighted the development of two new nuclear delivery systems, which, he said, could evade US anti-ballistic missile defenses.
This is essentially because neither of them are ballistic missiles, which are fired out of the atmosphere in a high-arcing trajectory.
One - effectively a very long-range nuclear-tipped torpedo - has been rumoured to be under development since Soviet days but is now seen by US analysts as a credible threat.
The second system - described by Mr Putin as a cruise missile - looks to be more of a work in progress and may be a kind of very high-speed "hypersonic" system - described by one arms control expert as a "glider on steroids" - that again could evade existing anti-missile defences.