NATO on Friday voiced concern over Russia's plans to restrict access to some parts of the Black Sea and Kerch Strait.
"This would be an unjustified move and part of a broader pattern of destabilising behaviour by Russia," NATO spokesperson Oana Lungescu said in a statement.
She called on Russia to "ensure free access to Ukrainian ports in the Sea of Azov, and allow freedom of navigation."
Lungescu said Russia has built up its military presence on and around the peninsula since it annexed Crimea illegally.
"The allies of NATO do not and will not recognize the illegal annexation of Crimea," she said.
In recent weeks, Russia has gathered combat-ready forces close to the Ukrainian border which is considered "the largest massing of Russian troops since the illegal annexation of Crimea in 2014," according to NATO Secretary General Jens Stoltenberg.
Russian forces entered Ukraine's Crimean Peninsula in February 2014, with Russian President Vladimir Putin formally dividing the region into two separate federal subjects of the Russian Federation the following month.
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Turkey and the US, as well as the UN General Assembly, view the annexation as illegal, as does the EU, which imposed sanctions on Russia for the seizure.