Dismissing more moderate voices, Biden is Putin's accuser-in-chief
US President Joe Biden's rhetoric on Ukraine has been more in line with Congress than with his own administration (AFP/MANDEL NGAN)

A "war criminal" and "butcher" who "cannot remain in power": over recent weeks, US President Joe Biden has steadily escalated his attacks on Russia's Vladimir Putin -- at the risk of wrong-footing allies, and even his own team.

The latest, most striking example: Biden's accusation of a Russian "genocide," during a Tuesday speech on biofuels and helping Americans with the cost of living.

Going further than any top administration official to date, Biden for the first time used the loaded term to characterize attacks on Ukrainian civilians by Putin's forces.

The White House, as in the past, prepped journalists behind the scenes that a clarification would be coming -- but, notably, none has.

Instead, asked later if he'd meant what he said, Biden doubled down.

"Yes, I called it genocide," said the president, adding that he would let lawyers decide "whether or not it qualifies" as such.

"It's become clearer and clearer that Putin is just trying to wipe out the idea of even being able to be a Ukrainian."

Addressing reporters Wednesday, the US envoy to the Organization for Security and Cooperation in Europe, Michael Carpenter, reiterated that it will be for international law experts to weigh the evidence and determine if Russia's actions meet the definition of genocide.

"That's going to take some time to be completed but in the meantime the president has made a very clear moral determination on this issue," he said.

Russian forces are accused of indiscriminate killings of Ukrainian civilians including in Bucha, on the outskirts of Kyiv, and the "genocide" remark also came amid unconfirmed reports of Moscow using chemical agents.

The Kremlin hit back at Biden's comment, calling it "hardly acceptable for the president of the United States" to "attempt to distort the situation in this way."

- 'True leader' -

Ukrainian President Volodymyr Zelensky was in no doubt what Biden's words signified.

"True words of a true leader... Calling things by their names is essential to stand up to evil," he tweeted.

White House officials have been more fastidious than the boss in staking out carefully-worded responses to each new development in the conflict -- yet Biden has repeatedly gone one step further.

Last week, he called reports of Russian atrocities in Ukraine a "war crime" but resisted using the term genocide.

He also called Putin a "war criminal" following Zelensky's highly-charged appeal to the US Congress for help last month, only for his officials to try to soften the remark later.

Biden's staffers were similarly caught off guard 10 days later in Poland when the president called Putin a "butcher" who "cannot remain in power."

The White House sprang into action, clarifying within minutes that Biden was not advocating "regime change."

Biden largely stood by his words, though later explaining the comments were not a policy change but an expression of "moral outrage."

The president has been criticized on each occasion but the frequency of the controversies might suggest he is deliberately dragging more cautious aides into a tougher stance against Russia.

Bombarded by reporters' questions Wednesday on Biden's slipping "genocide" into a speech about US gasoline prices, White House spokeswoman Jen Psaki said: "He's the president of the United States and the leader of the free world and he is allowed to make his views known at any point he would like to."

- 'It's madness' -

While Secretary of State Antony Blinken and National Security Advisor Jake Sullivan have declined to use the word "genocide," Biden is sure to have pleased hawks from both parties on Capitol Hill, who have been pressuring the White House towards a more strident response.

"It is a genocide," Chuck Schumer, the leader of Biden's Democrats in the Senate, said on April 6.

"When these people are shot simply because of their nationality, they don't have arms, that's genocide -- especially when it occurs in the large numbers it has already."

Other leaders in the Western alliance have been more reserved.

French President Emmanuel Macron criticized the use of the term "butcher" and has refused to follow Biden in using the term "genocide."

"I want to try as much as possible to continue to be able to stop this war and to rebuild peace," he said. "I'm not sure that verbal escalations serve this cause."

A European diplomat told AFP Biden was trying to thread the needle of speaking in terms that would be sufficiently robust to satisfy Congress while avoiding harming the pursuit of a negotiated settlement.

The president Wednesday announced a new $800 million military aid package for Ukraine, including armored personnel carriers and helicopters, as it faces a revamped Russian offensive in the Donbas region.

But he has ruled out sending troops or getting involved in the conflict by any other means, meaning the only option still on the table for attacking Putin is the occasional verbal broadside.