A top Russian official on Tuesday warned Ukraine that any attempt to retake control over the illegally annexed peninsula of Crimea will be seen as a "declaration of war" by Moscow.

Despite international condemnation and the largest conflict in Europe since World War II, Russian President Vladimir Putin has maintained his invasion amounts to a "special military operation," not an official declaration of war. 

"For us, Crimea is part of Russia. And it shall be forever. Any attempt to encroach on Crimea is a declaration of war on our country," Deputy Chairman of Russia’s Security Council Dmitry Medvedev told Russian media Tuesday.

Service members take part in a military parade on Victory Day, which marks the 77th anniversary of the victory over Nazi Germany in World War II, in the Chechen capital Grozny, Russia May 9, 2022. REUTERS/Chingis Kondarov

Service members take part in a military parade on Victory Day, which marks the 77th anniversary of the victory over Nazi Germany in World War II, in the Chechen capital Grozny, Russia May 9, 2022.  (REUTERS/Chingis Kondarov)

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Medvedev once again reiterated Russia’s objection to Ukraine joining NATO and suggested if it were to do so amid the ongoing conflict the result would be "catastrophic."

The Russian official said the push for Sweden and Finland to join NATO "does not threaten Russia with anything particularly new."

But added that if Ukraine were to try to enter the military alliance, it would be "much more dangerous due to the existence of unresolved territorial disputes."

Medvedev said if a NATO member encroached on Crimea it would mean "conflict with the entire North Atlantic Alliance. World War III. A total catastrophe."

While Sweden and Finland continue negotiations with Turkey on NATO admittance, no such moves have been made with Ukraine. 

Woman wrapped in Ukrainian flag

A woman wrapped in a Ukrainian flag attends the funeral of activist and soldier Roman Ratushnyi in Kyiv, Ukraine, Saturday, June 18, 2022. Ratushnyi died in a battle near Izyum, where Russian and Ukrainian troops are fighting for control of the area.  (AP)

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In the lead-up to Russia’s February invasion, Ukrainian President Volodymyr Zelenskyy said he would work to regain the Crimean Peninsula after Moscow illegally annexed it in 2014. 

Putin, who held a referendum on the annexation – which the UN and international community have decried as illegitimate – has said similar votes will be held in other parts of Ukraine. 

Zelenskyy has vowed to keep fighting Russia until its forces are pushed out of Ukraine but acknowledged last month that removing Russian troops from Crimea militarily will likely not be an option.

Ukrainian serviceman

A Ukrainian serviceman stands in an observation point near the frontline village of Krymske, Luhansk region, in eastern Ukraine, Saturday, Feb. 19, 2022.  (AP Photo/Vadim Ghirda)

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"I do not believe that we can restore all of our territory by military means. If we decide to go that way, we will lose hundreds of thousands of people," he said.

Though Zelenskyy was adamant that "Ukraine will get everything back. Everything."