KYIV, Ukraine

Ukraine has lost control of the Chernobyl nuclear power plant in the country’s north after a fierce battle with Russian forces, Ukraine’s presidential advisor said on Thursday. 

Speaking to Ukraine's Unian news agency, Mykhailo Podolyak said the latest Russian move constitutes one of the biggest threats to European security.

Earlier, the Ukrainian president said that Russian forces are trying to seize the Chernobyl nuclear power plant.

With an obvious reference to the importance of the site, where a devastating nuclear accident occurred in 1986, Volodymyr Zelenskyy said: “This is a declaration of war against the whole of Europe.”

The February 2014 “Maidan revolution” in Ukraine led to former President Viktor Yanukovych fleeing the country and a pro-Western government coming to power.

That was followed by Russia illegally annexing the Crimea region and separatists declaring independence in the Donetsk and Luhansk regions of Donbas in eastern Ukraine, both of which have large ethnic Russian populations.

As clashes erupted between Russian-backed separatist forces and the Ukrainian army, the 2014 and 2015 Minsk agreements were signed in Moscow after the intervention of Western powers.

The conflict, however, simmered for years with persistent cease-fire violations.

As of February 2022, some 14,000 people have been killed in the conflict in eastern Ukraine.

Tensions started escalating late last year when Ukraine, the US and its allies accused Russia of amassing tens of thousands of troops on the border with Ukraine.

They claimed Russia was preparing to invade its western neighbor, allegations that were consistently rejected by Moscow.

Defying threats of sanctions by the West, Moscow officially recognized Donetsk and Luhansk as independent states earlier this week, followed by the start of a military operation in Ukraine on Thursday.

President Putin said the operation aims to protect people “subjected to genocide” by Kyiv and to “demilitarize and denazify” Ukraine, while calling on the Ukrainian army to lay down its arms.

* Writing by Zehra Nur Duz