Moscowinfo-icon: Russian President Vladimir Putin has announced a special "military operation" to protect Donbas, the separatist-held region in eastern Ukraine, mediainfo-icon reports said on Thursday. Putin made a surprise statement on television to declare his intentions.

"I have made the decision of a military operation," he said shortly before 6:00 am (0300 GMT) in Moscow, as he vowed retaliation against anyone who interfered, news agency AFP reported.

This comes hours after Ukrainian President Volodymyr Zelenskyy said Ukraineinfo-icon has not posed and will not pose a threat to Russiainfo-icon. In an emotional appeal delivered largely in Russian, Zelenskyy said "You are being told that Ukraine can pose a threat to Russia.

"It was not like this in the past, it is not like this now and it will not be so in the future. You demand security guarantees from NATO. We also demand guarantees of our security - from you, from Russia, and other guarantors of the Budapest memorandum," Zelenskyy said in a video address.

Ukrainian President also refuted Moscow's claims that his country poses a threat to Russia and warned that a Russian invasion would cost tens of thousands of lives.The White House warned on Wednesday that Putin will face significant consequences if Moscow invades Ukraine.

Meanwhile, an emergency session of the UN Security Council on the prevailing situation in Ukraine is underway.

Ukraine requested an urgent United Nationsinfo-icon Security Council (UNSC) Meet after Heads of the Ukraine breakaway regions, Donetsk and Luhansk, have asked the Russian President for help.

Putin has also ordered the sending of the Russian Armed Forces to Ukraine's breakaway regions.

Meanwhile, the Ukrainian parliament, Verkhovna Rada, approved declaring a state of emergency in the whole country except for Donetsk and Luhansk regions amid the escalating situation at the country's borders. 

Ukraine Crisis

Putin has defied a barrage of international criticism over the crisis, with some Western leaders saying he was no longer rational.

The 27-nation bloc had also imposed sanctions on Russia's defence minister Sergei Shoigu and high-ranking figures including the commanders of Russia's armyinfo-icon, navy and air force, another part of the wave of Western punishment after Putin sought to rewrite Ukraine's borders.

The United Nations Security Council met late Wednesday for its second emergency session in three days over the crisis, with a personal plea there by UN Secretary-General Antonio Guterres to Putin going unheeded.

"President Putin, stop your troops from attacking Ukraine, give peace a chance, too many people have already died," Guterres said.

Ukraine has around 200,000 military personnel and Wednesday's call up could see up to 250,000 reservists aged between 18 and 60 receive their mobilisation papers.

Moscow's total forces are much larger -- around a million active-duty personnel -- and have been modernised and re-armed in recent years.

High Cost Of Warinfo-icon

But Ukraine has received advanced anti-tank weaponsinfo-icon and some drones from NATO members. More have been promised as the allies try to deter a Russian attack or at least make it costly.

Russia has long demanded that Ukraine be forbidden from ever joining the NATO alliance and that USinfo-icon troops pull out from Eastern Europe.

Speaking to journalists, Putin on Tuesday set out a number of stringent conditions if the West wanted to de-escalate the crisis, saying Ukraine should drop its NATO ambition and become neutral.

Washington Wednesday announced sanctions on the Nord Stream 2 gas pipeline, which Germanyinfo-icon had earlier effectively suspended by halting certification.

Australiainfo-icon, Britaininfo-icon, Japaninfo-icon and the European Unioninfo-icon have all also announced sanctions.