The White House warned Russia that there would be "catastrophic consequences" if the latter uses nuclear weapons in Ukraine, US national security adviser Jake Sullivan said Sunday.

Sullivan's words came after Russian Foreign Minister Sergey Lavrov said Saturday on the sidelines of the 77th session of the United Nations General Assembly that any territory recognized by the Russian constitution as Russian territory falls under Moscow's full protection.

"The entire territory of the Russian Federation, which is confirmed and can be further confirmed in the Russian Constitution, is certainly under the state’s full protection," Lavrov said.

"All laws, doctrines, concepts, strategies of the Russian Federation apply to its entire territory," he stressed.

All of the situations under which Russia can use nuclear weapons are clearly specified in the country's military doctrine, the Russian foreign minister underlined.

Sullivan told ABC on Sunday that the White House had taken Moscow's warning seriously and urged him to refrain from using nuclear weapons.

"We have communicated directly and privately to the Russians at very high levels that there will be catastrophic consequences for Russia if they use nuclear weapons in Ukraine," he said.

The White House official claimed Russia understood well what it would face "if they went down that dark road." The official revealed that his country was "planning for every contingency and would respond decisively to Russia."

"As for the Russian Federation, the president and other Kremlin representatives have stated this on numerous occasions; we have our nuclear security doctrine. It is a document available to the public. Everything is written down in it. I invite you to look once again at absolutely clearly specified cases when our use of nuclear weapons is allowed," Lavrov added.

Russian Deputy Foreign Minister Sergey Ryabkov said on Friday that the United States is incapable of holding negotiations, and it is joining forces with its allies to push Kiev to move against Russia and its territories in an attempt to defeat Moscow.

Ryabkov said the US deliberately lowered the nuclear threshold, thus, posing threat to Russia's nuclear security.

Russian President Vladimir Putin had also accused the west of using the threat of nuclear weapons to blackmail Russia and warned that Moscow will use all means in case its territorial integrity is threatened.

The Russian ambassador to the United States, Anatoly Antonov, said Friday he wanted to believe his country and the United States were not yet on the verge of nuclear war despite there being many difficulties in their relations.

"With each day, that little, which still glimmers in contacts between the two countries, is fading away. I want to believe that despite all the difficulties, Americans and we are yet to be on the verge of a nuclear conflict," Antonov added.