Smoke from an artillery explosion in Donetsk on February 19. VNA photo

MOSCOW — Russia has begun a military operation in Ukraine following a request from the authorities of the Donetsk and Lugansk republics for assistance in repelling Kiev’s military aggression, Russian President Vladimir Putin said in an urgent address on Thursday.

He said that Moscow would seek the "demilitarization and denazification" of Ukraine, called upon the Ukrainian army to lay down weapons and warned there would follow a prompt response to attempts at foreign intervention from outside.

After that there followed reports of sounds of explosions in a number of Ukrainian cities, including Kiev and Kharkov.

Military operation

TASS said after a message from the Donbass republics Putin made a decision to conduct a "special military operation".

"Its purpose is to protect the people who have for eight years been exposed to humiliation and genocide by the regime in Kiev. For this we will seek demilitarization and denazification of Ukraine, and also press for bringing to justice those who have committed numerous bloody crimes against peaceful civilians, including Russian citizens."

Moscow’s plans do not include an occupation of Ukraine, according to the report. It is for the right of the Ukrainian people to self-determination. Also, Putin said that Russia could not let Kiev obtain nuclear weapons and recalled NATO’s illegitimate expansion to the east.

Address to Ukrainians

Putin urged the Ukrainian military to "lay down arms at once and leave for home."

"Those servicemen of the Ukrainian army who will meet this demand will be free to leave the zone of combat operations and return to their families." All responsibility for possible bloodshed "will rest upon entirely on Ukraine’s ruling regime."

In his address to the Ukrainian people, he explained that Russia’s actions were taken in self-defence from threats and from a "still greater misfortune than the one happening today".

"However difficult it may be to do this, I am asking you to understand this and calling for cooperation in order to turn this tragic page as soon as possible and to move forward together."

Warning to others

Putin warned against attempts at foreign intervention in the current developments, let alone foreign intervention.

"Nobody should feel any doubts that a direct attack on Russia would end with the potential aggressor’s defeat and terrible consequences for the attacker," he warned.

"Whoever may try to create obstructions to us, let alone pose threats to our country and our people, they should know that Russia’s response will follow without delay and entail consequences that you have never encountered in your history. We are prepared for any march of events. All necessary decisions in this connection will be made. I hope that I will be heard," Putin said.

First western reaction

Immediately after that US President Joseph Biden made a written statement, in which he blamed Russia for what he described as "a premeditated war that will bring a catastrophic loss of life and human suffering," and warned that "the United States and its Allies and partners will respond in a united and decisive way."

Biden said that later on Thursday he would make a special address to announce further measures against Russia Washington and its allies would take.

NATO’s Secretary-General Jens Stoltenberg has said that a meeting of the alliance’s member-countries will consider the effects of Russia’s actions towards Ukraine.

Biden also held a phone call with his Ukrainian counterpart Volodymyr Zelensky soon after explosions were heard in multiple parts of the country, which is sandwiched between Russia and NATO member Poland.

"We will continue to provide support and assistance to Ukraine and the Ukrainian people," Biden said in a statement after the call, adding that Zelensky had requested him to "call on the leaders of the world to speak out clearly" against Putin's "flagrant aggression".

The US Secretaries of State and Defense also spoke with NATO chief Jens Stoltenberg to condemn the "unprovoked, and unjustified attack on Ukraine", the State Department said.

President Biden was due to join a virtual, closed-door meeting of G7 leaders – Britain, Canada, France, Germany, Italy, Japan and the United States – at 9am (1400 GMT) on Thursday. The White House said his remarks to the nation would come in the early afternoon in Washington. The G7 meeting is likely to result in more sanctions against Russia.

On Tuesday, the US government joined European allies in imposing sanctions on two Russian banks, Moscow's sovereign debt, several oligarchs and other measures.

And on Wednesday, Biden announced he was imposing sanctions on the Nord Stream 2 natural gas pipeline from Russia to Germany – one of energy-rich Moscow's highest-profile energy and geopolitical projects. Germany had earlier announced it would block the pipeline from opening for deliveries.

The United States and other United Nations Security Council members slammed Russian President Vladimir Putin on Wednesday for attacking Ukraine as the 15-member body met in New York to try and defuse weeks of mounting tensions.

"At the exact time as we are gathered in the council seeking peace, Putin delivered a message of war in total disdain for the responsibility of this Council. This is a grave emergency," US Ambassador Linda Thomas-Greenfield told the council.

UN Secretary-General Antonio Guterres told reporters after the council meeting it was "the saddest moment" in his more than five years in the job, appealing: "President Putin, in the name of humanity bring your troops back to Russia."

"This conflict must stop now," he said.

Russia's UN Ambassador Vassily Nebenzia notified the council of Moscow's move during the meeting, justifying it under Article 51 of the U.N. Charter, which covers individual or collective self-defence by states against armed attack.

Britain's UN Ambassador Barbara Woodward described Russia's move on Ukraine as "unprovoked and unjustified".

"We believe that the door to a peaceful solution to the Ukraine issue is not fully shut, nor should it be," China's UN Ambassador Zhang Jun told the Security Council as the violence escalated in Ukraine.

Ukraine's UN Ambassador Sergiy Kyslytsya said Russia had just declared a war on his country and told Nebenzia at the end of the council meeting: "There is no purgatory for war criminals. They go straight to hell."

Nebenzia responded: "We aren't being aggressive against the Ukrainian people, but against the junta that is in power in Kyiv." — TASS/AFP/REUTERS