Top officials say any Russian decision to move nuclear weapons to Crimea would significantly worsen East-West tensions
Ukraine's defence minister accused Russia on Wednesday of preparing to potentially store nuclear weapons in Crimea and warned that Moscow could attack Ukraine to ensure water supplies for the annexed peninsula.
Andrii Taran, speaking just before an emergency Nato meeting with allied defence and foreign ministers, also said he could not rule out a possibility that Russian forces in Crimea could "undertake substantive military provocations" this year.
Russia annexed Crimea from Ukraine in March 2014, in a move that triggered western sanctions against Moscow.
"Crimea's infrastructure is being prepared for potentially storing nuclear weapons," Taran told the European Parliament's sub-committee on defence. "The very presence of nuclear munitions in the peninsula may spark a whole array of complex political, legal and moral problems."
Taran provided no evidence for his assertion but said Russia was massing 110,000 troops on Ukraine's border in 56 battalion-sized tactical groups, citing the latest Ukrainian intelligence.
Russia says it is Nato, not Moscow, that is carrying out threatening military action in Europe.
Defence Minister Sergei Shoigu said on Tuesday its force manoeuvres were part of legitimate drills to test combat readiness.
Any Russian decision to move nuclear weapons to Crimea would mark a significant worsening in East-West tensions.
It would also strain a newly-extended arms control treaty between the United States and Russia, which imposes restrictions on land- and submarine-based missiles used to carry nuclear warheads.
Fighting has increased in recent weeks in eastern Ukraine, where government forces have battled Russian-backed separatists in a seven-year conflict that Kyiv says has killed 14,000 people. Nato says the number of Russian troops massed on Ukraine's borders is the highest since 2014.
For Washington and its European allies, Ukraine is the highest-profile test of a decades-long policy to build a ring of Western-aligned democracies on Russia's western flank, though it has not offered Kyiv membership of Nato or the European Union.
US Secretary of State Antony Blinken, in Brussels to discuss strategy with allies, referred to a "massive military buildup" of Russian troops. He said Nato would "address Russia's aggressive actions in and around Ukraine", without elaborating.
Full-blown conflict would impoverish Ukraine and lead to more Western sanctions on Russia, diplomats and analysts said.
Concerns about an escalation were partly assuaged after a phone call on Tuesday between US President Joe Biden and his Russian counterpart Vladimir Putin .
German Defence Minister Annegret Kramp-Karrenbauer told German public TV channel ARD that Russia was wrong not to have forewarned Nato about its war games, saying that Putin was "waiting for a move (by Kyiv) towards Nato to have an excuse to continue his actions".
Taran described Russia's movements as "potentially offensive military exercises" that could be used to "conduct unpredictable, escalating actions" from Crimea.
He said Russia has up to 42,000 military personnel stationed in Crimea, as well as naval and air capabilities.
US Defense Secretary Lloyd Austin met Nato Secretary-General Jens Stoltenberg at Nato headquarters on Wednesday to discuss Ukraine ahead of the meeting of all 30 allies by video conference.