In response to Wednesday's words by Russian President Vladimir Putin, in which he threatened to deploy nuclear weapons in the Ukraine crisis, US officials have made it apparent that they are actively debating the possibility of a nuclear exchange.

"We have communicated directly, privately, and at very high levels to the Kremlin that any use of nuclear weapons will result in catastrophic consequences for Russia, that the United States and our allies will respond decisively, and we have been clear and specific about what that will entail," US National Security Advisor Jake Sullivan told CBS interview host Margaret Brennan on Sunday.

The prospective use of nuclear weapons for the first time since World War II, he warned, is a matter of the utmost gravity.

The New York Times reported later that day that US officials believe the likelihood of nuclear escalation is "considerably greater than in February and March."

The Financial Times said that the United States and its allies are "increasing nuclear vigilance and deterrence," citing five western officials who spoke anonymously because of the delicacy of the subject.

The Financial Times also stated, citing a high-ranking official, that the United States had reviewed with the Ukrainians hypothetical nuclear use scenarios and talked through "protection and safety."

In his appearances on Sunday talk shows in the United States, Sullivan corroborated a report published Thursday in the Washington Post that US officials had made "private communications to Moscow warning Russia's leadership of the grave consequences of using a nuclear weapon."

Sullivan's threats were made more explicit. He warned Chuck Todd, moderator of "Meet the Press," that the repercussions would be "catastrophic" if Russia used nuclear weapons.

In response to Todd's request for clarification, Sullivan said, "Should Russia breach this boundary, terrible consequences will ensue for Russia. The United States will react forcefully."

Sullivan responded to Todd's question as to whether the repeated use of the term "catastrophic" means "as bad as he could imagine" by stating, "Russia understands very well what the United States would do in response to the use of nuclear weapons in Ukraine because we have spelled it out for them, and I will leave it at that for today."

In other words, while the Russian leadership has been told of the dangers of Russia's use of nuclear weapons in Ukraine, the American people, who would be annihilated if the United States initiated a complete strategic nuclear exchange, will remain in the dark.

Russia held referendums for membership in the Russian Federation in four districts of Eastern Ukraine under its military control: Luhansk, Donetsk, Kherson, and Zaporizhzhia. On Sunday, the third day of voting was held.

Russian Foreign Minister Sergei Lavrov stated on Saturday that any regions annexed to Russia will be "under the full protection of the state," meaning that Russia would respond to any attacks on them with nuclear weapons.

On Thursday, the Russian parliament may vote to merge the provinces into the Russian Federation, and Putin is provisionally scheduled to address the legislature on Friday.

In an interview with CNN, British Prime Minister Liz Truss made it plain that Putin's warning of nuclear escalation will not reduce the United Kingdom's commitment to the conflict. "We should not listen to his empty threats and saber-rattling. Instead, we must continue to impose sanctions on Russia and help the Ukrainians, as stated by Truss.

The US media went all out to justify the probable use of nuclear weapons in the fight in response to Sullivan's threats.

In possibly the most extreme instance, New York Times columnist Ross Douthat speculated that "Kiev may be willing to accept an unusual level of nuclear risk, or even absorb a nuclear strike, in order to preserve its territorial integrity." In a fight for their very freedom, the Ukrainians want their children to say, "During the greatest crisis, their fathers' blood ran strong."

In a previous commentary on the World Socialist Web Site, we stated that the strategists and propagandists of US imperialism view the people of Ukraine as "cannon fodder." There is no greater confirmation of this than the suggestion that the impoverished Eastern European nation would "absorb" a nuclear attack capable of killing millions of people.

The increasingly evident reality that the conflict is swiftly threatening to develop into a nuclear war has not been viewed as an incentive to pursue a negotiated conclusion of the war, which has already claimed the lives of tens of thousands of people and displaced millions.

Rather, the United States views any Russian escalation of the conflict in the aftermath of the military defeat in northern Ukraine as an opportunity to escalate its engagement in the fight. According to a Sunday op-ed by Times columnist David Brooks, US authorities want to continue supplying Ukraine with armaments, maybe including tanks and modern jet planes. These systems seem to be on the table."