MOSCOW,
 Sept 18 (Reuters) - The Kremlin on Wednesday described as "dangerous" 
comments by Jens Stoltenberg, the outgoing head of NATO, that a decision
 by the West to allow Ukraine to use Western long-range weapons to 
strike Russia would not be a red line that would prompt an escalation by
 Moscow.
Ukrainian
 President Volodymyr Zelenskiy has been pleading with allies for months 
to let Ukraine fire Western missiles including long-range U.S. ATACMS 
and British Storm Shadows into Russia to limit Moscow's ability to 
launch attacks.
In
 an interview with The Times published on Tuesday, Stoltenberg dismissed
 a warning by Russian President Vladimir Putin last week that letting 
Ukraine use such weapons to strike deep inside Russian territory would 
mean the West was directly fighting Russia.
"There
 have been many red lines declared by him before, and he has not 
escalated, meaning also involving NATO allies directly in the conflict,"
 said Stoltenberg, whose tenure as head of the military alliance ends in
 October.
"He
 has not done so, because he realises that NATO is the strongest 
military alliance in the world. They also realise that nuclear weapons, 
nuclear war, cannot be won and should not be fought. And we have made 
that very clear to him several times."
Kremlin spokesman Dmitry Peskov told reporters that Stoltenberg's remarks were dangerous.
"This
 ostentatious desire not to take seriously the Russian president's 
statements is a move that is completely short-sighted and 
unprofessional," said Peskov.
Stoltenberg's position is "extremely provocative and dangerous," Peskov added.
A
 senior NATO military official said over the weekend that Ukraine would 
have good military reason to strike deeper into Russia using Western 
weapons. Kyiv's allies, including the United States and Britain, are 
currently discussing whether to give Kyiv a green light to do so.
Senior
 Russian politicians and foreign policy hawks have suggested that Moscow
 could respond with nuclear weapons. The head of Russia's nuclear 
testing site said on Tuesday that his facility was ready to resume 
testing "at any moment." Russia has the world's largest nuclear arsenal.
In
 the course of the war, Washington and its allies have increased 
military aid to Ukraine in ways that were unthinkable when it started, 
including by providing tanks, advanced missiles and F-16 fighter jets.
That
 has prompted some Western politicians to suggest Putin's nuclear 
rhetoric is a bluff and that the U.S. and NATO should go all-out to help
 Ukraine win the war. Zelenskiy has said Ukraine's incursion into 
Russia, launched on Aug. 6, makes a mockery of Putin's red lines.
Dmitry Antonov; Writing by Lucy Papachristou; Editing by Andrew Osborn and Mark Trevelyan