The head of the United Nations implored Russian President Vladimir Putin on Wednesday night not to attack Ukraine and to “give peace a chance,” a plea made just minutes before Putin announced a military operation in Ukraine.

The televised announcement came as U.N. Security Council members were pressing Russia to reverse course. The council had hastily gathered for an emergency meeting hours after Russia said rebels in eastern Ukraine had asked Moscow for military assistance, an announcement that immediately fueled fears that Moscow was laying the groundwork for war.

“If indeed an operation is being prepared, I have only one thing to say from the bottom of my heart: President Putin, stop your troops from attacking Ukraine. Give peace a chance. Too many people have already died,” U.N. Secretary-General Antonio Guterres told the council.

Read:Russia evacuating embassy in Ukraine as crisis escalates

Less than a half hour later, while members called on Russia to halt its confrontational moves, Putin announced a military operation that he said was meant to protect civilians. He warned other countries that any effort to interfere with the Russian operation would lead to “consequences they have never seen.”

It wasn’t immediately clear whether council members were aware of the development.

The council, where Russia holds the rotating presidency this month, was meeting just two days after another emergency session where other members expressed no support for Moscow’s decision to recognize two rebel regions of Ukraine as independent and to order Russian troops there for “peacekeeping.”

Council diplomats are now finalizing a draft of a resolution that would declare that Russia is violating the U.N. Charter, international law, and a 2015 council resolution on Ukraine, a diplomat said, speaking on condition of anonymity because the discussions were private. The resolution would urge Russia to come back into compliance immediately, the diplomat said.

Read: Ukraine's economy is another victim of Russia's 'hybrid war'

Earlier Wednesday, diplomats from dozens of countries took the floor at the U.N. General Assembly to deplore Russia’s actions toward the country and plead for diplomacy.

Russia and ally Syria defended Moscow’s moves. But even China, which usually takes Russia’s side at the U.N., spoke up for the world body’s longstanding principle of respecting countries’ sovereignty and internationally recognized borders, while not mentioning Russia by name.

Echoing a narrative being broadcast to Russians at home, Russian Ambassador Vassily Nebenzia portrayed his country as responding to the plight of beleaguered people in the breakaway areas. Russia claims Ukraine is engaging in violence and oppression, which Ukraine denies.

“We urge you today to focus on reining in Kyiv,” Nebenzia said.

Syria accused the West of using the assembly to pressure Moscow.

“The Ukrainian crisis was created by the Western states, led by the United States, to divide people and to undermine Russian security,” Ambassador Bassam al-Sabbagh said.

Meeting a day after Western powers and some other countries imposed new sanctions on Russia, the 193-member General Assembly didn’t take any collective action. But the comments from nearly 70 nations, with more scheduled for Monday, represented the broadest forum of global sentiment since the crisis dramatically escalated this week.

Ukrainian Foreign Minister Dmytro Kuleba implored countries to use tough economic sanctions, strong messages and “active diplomacy” to get Russia to back off. A lackluster response would jeopardize not only Ukraine but the concept of international law and global security, he warned.

“We need to use this last chance for action and stop Russia where it is,” Kuleba said.

Russia seized Ukraine’s Crimea Peninsula in 2014, and pro-Russia rebels have since been fighting Ukrainian forces in the eastern areas of Donetsk and Luhansk. More than 14,000 people have been killed in the conflict.

After weeks of rising tension as Moscow massed over 150,000 troops on Ukraine’s borders, Russian President Vladimir Putin on Monday recognized the two regions’ independence and ordered Russian forces there as what he called “peacekeepers.”

Guterres disputed that, saying they are troops entering another country without its consent.