Russia-Ukraine updates: Putin suspends key US-Russia nuclear treaty in speech denouncing West

Newly recruited Russian soldiers are reporting for duty in response to the Kremlin's emergency mobilization to bolster forces in Ukraine, according to photographs emerging from Russia.

Images taken by Associated Press photographers showed Russian recruits gathered at recruitment centers on Sunday in Volgograd and Krasnoda, Russia, some bidding emotional farewells to loved ones as they boarded buses.

Russian President Vladimir Putin announced last week a mobilization to draft more than 300,000 Russians with military expertise, sparking anti-war protests across the country and prompting many to try to flee Russia to avoid the draft.

Putin signed a law with amendments to the Russian Criminal Code upping the punishments for the crimes of desertion during periods of mobilization and martial law.

White House national security adviser Jake Sullivan said in an interview Sunday with ABC "This Week" anchor George Stephanopoulos that Russia's military draft is more evidence Russia is "struggling" in its invasion of Ukraine. He also said "sham referendums" going on in Russia-backed territories of eastern and southern Ukraine are also acts of desperation by the Kremlin.

"These are definitely not signs of strength or confidence. Quite the opposite: They're signs that Russia and Putin are struggling badly," Sullivan said while noting Putin's autocratic hold on the country made it hard to make definitive assessments from the outside.

Russian President Vladimir Putin signed a law with amendments to the Russian Criminal Code imposing more severe punishments for the crimes of desertion, looting and surrender during periods of mobilization and martial law, according to the official portal of legal information.

The law introduces the notions of "mobilization," "martial law" and "wartime" and adds a number of new articles to the Criminal Code.

This comes days after Putin announced a mobilization expected to draft more than 300,000 Russians with military expertise. Anti-war protests have broken out in response to news of the draft and many have tried to flee Russia.

The article criminalizing "looting" has been amended to provide for up to 15 years of imprisonment. Commission of the crime "during a period of mobilization or martial law, in wartime" is deemed an extenuating circumstance.

Failure by a subordinate to obey an order issued by a superior in due manner during a period of martial law, in wartime or in conditions of an armed conflict or the conduct of hostilities, as well as a refusal to participate in military action or combat, will be punished by imprisonment of two to three years. If severe consequences ensue, such actions will be punished by three to ten years of imprisonment.

Furthermore, reservists will be criminally liable for arbitrary abandonment of a unit or base and for failure to report for duty in due time without a good reason during their recruit military training. This acts will be punishable with up to 10 years of imprisonment, depending on the severity of the act.

The law also introduces a number of articles regarding a failure to execute a state defense order and a violation of the terms of a state contract.

President Joe Biden issued a statement Friday evening again calling the referendums in Russian-controlled Ukrainian territory a "sham."

"The United States will never recognize Ukrainian territory as anything other than part of Ukraine," he said in his statement.

Biden added that the U.S. "will work with our allies and partners to impose additional swift and severe economic costs on Russia."

He said the U.S. will join with other nations "in rejecting whatever fabricated outcomes Russia will announce."

-ABC News' Ben Gittleson

White House press secretary Karine Jean-Pierre declined to comment on reports that the U.S. has sent private warnings to Russia over its nuclear threats.

During her on camera briefing with reporters, Jean-Pierre she said the threats still haven’t given the U.S. reason to adjust its own nuclear posture.

“We obviously take these threats very seriously,” she said. “But we have not seen any reason to adjust our own nuclear posture at this time."

Jean-Pierre also declined to say if the President Joe Biden would support providing asylum to Russians fleeing conscriptions.

“What we're seeing in Russia, especially with the protests, and what we're seeing with Russians leaving their country is that this is an unpopular war,” she said.

-ABC News' Ben Gittleson