More than 500,000 NATO military personnel are currently on high alert, the US-led military bloc's spokesperson, Farah Dakhlallah, confirmed on Sunday.

"Since 2014, NATO has undergone the most significant transformation in our collective defense in a generation," Dakhlallah told CNN.

"We have put in place the most comprehensive defense plans since the Cold War, with currently more than 500,000 troops at high readiness," she indicated.

The announcement follows the Washington Summit Declaration, where NATO leaders confirmed that Ukraine is on an "irreversible path" into the alliance.

The statement emphasized NATO's commitment to isolating Russia, strengthening security on its eastern flank, and increasing military assistance to Ukraine.

Dmitry Medvedev, Russia’s Security Council deputy chairman, warned last week that Ukraine’s accession into NATO would be a declaration of war against Russia, pointing out that global catastrophe can only be prevented through the alliance’s prudence.

"This, in essence, would be a declaration of war - albeit with a delay," he said in remarks published on Wednesday.

Medvedev told Argumenty I Fakty that Ukraine’s accession would pose more than just a direct security threat to Russia.

"The more such attempts there are, the harsher our answers will become," he affirmed, responding to NATO's intent to advance its interests and expand the alliance.

"Whether this will shatter the entire planet into pieces depends solely on the prudence of (NATO) side."

"For Russia, nothing will change, since key decisions are made not by NATO member countries, but by one state - the United States," Medvedev said regarding Mark Rutte’s appointment as the head of NATO.

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