The United States of America on Sunday warned Russia about the catastrophic consequences of using nuclear weapons in Ukraine.
Washington has pledged to give a “decisive response” if the Kremlin decides to take this step, said Jake Sullivan, US President's National Security Adviser.
"If Russia crosses this border, the consequences for Russia will be catastrophic. The United States will respond decisively. Now, through private channels, we have explained in more detail what this means," said Sullivan.
The US official suggested that Washington was developing a plan "for all cases".
Sullivan also confirmed that the US was already working on new anti-Russian sanctions that would be imposed against organizations, individuals and companies that support the Russian “military machine and illegal referendums in the occupied territories of Ukraine”.
However, Sullivan refrained from commenting on the protests against the mobilization in Russia.
He said that the United States of America was focused on supporting Ukraine and "the future of Russia should be decided by the Russian people".