Russia-Ukraine updates: US sanctions Russian military shipbuilder, diamond miner

President Joe Biden told reporters Monday that when he said in Poland this weekend that Russian President Vladimir Putin "cannot remain in power," he "was expressing moral outrage that I feel," adding, "I make no apologies for it."

Biden did not dispute when a questioner noted the line had not been in his prepared remarks.

"The last part of the speech was talking to the Russian people, telling them what we thought. I was communicating this to not only the Russian people but the whole world. This is -- this is just stating a simple fact that this kind of behavior is totally unacceptable. Totally unacceptable. And the way to deal with it is to strengthen and put -- keep NATO completely united and help Ukraine where we can," Biden said.

"I want to make it clear, I wasn't then, nor am I now, articulating a policy change," Biden said.

"The last thing I want to do is engage in a land war or a nuclear war with Russia," he said. "That's not part of it. I was expressing my outrage at the behavior of this man."

Biden said that if Putin "continues on this course that he's on, he is going to become a pariah worldwide."

He said he didn't think his comments complicated diplomatic efforts, but that it is Putin’s actions that are complicating the situation.

"He shouldn't remain in power. Just like, you know, bad people shouldn't continue to do bad things. But it doesn't mean we have a fundamental policy to do anything to take Putin down in any way," Biden said.

The president said "it’s ridiculous" to think his remark was a statement of U.S. policy.

"People like this shouldn't be ruling countries, but they do. The fact they do doesn't mean I can't express my outrage about it," he said.

Biden told ABC News that he’s confident Putin won’t view his remarks as an excuse for escalation.

"The idea that he is going to do something outrageous because I called him for what he was and what he's doing, I think is just not rational," Biden said.

-ABC News' Ben Gittleson

United Nations Secretary-General António Guterres on Monday appealed for an immediate humanitarian ceasefire in Ukraine.

"Since the beginning of the Russian invasion one months ago, the war has led to the senseless loss of thousands of lives, the displacement of 10 million people, mainly women and children, the systematic destruction of essential infrastructure and skyrocketing food and energy prices worldwide. This must stop," Guterres said.

U.N. humanitarian agencies and partners in the last month have reached nearly 900,000 people, mainly in eastern Ukraine, providing food, shelter, blankets, medicine, bottled water and hygiene supplies, he said.

-ABC News' Christine Theodorou

The Pentagon said it's sending six U.S. Navy EA-18 "Growlers" (Navy fighter aircraft equipped with electronic warfare jamming equipment) and 240 personnel to Germany to boost NATO's defenses because of the aircraft's electronic warfare jamming capability.

"They are not being deployed to be used against Russian forces in Ukraine," Pentagon spokesman John Kirby stressed. "They are being deployed completely in keeping with our efforts to bolster NATO's deterrence and defense capabilities along that Eastern flank. They are not being sent because of some sort of acute threat that was perceived or some specific incident that happened."

"This is in order to bolster readiness, enhance NATO's collective defense posture and further increase air integration capabilities with our Allied and partner nations," Kirby said.

-ABC News' Luis Martinez

The Russians appear to be prioritizing the Donbas region in eastern Ukraine, a senior U.S. defense official told reporters on Monday.

“We're not exactly sure what's behind this reprioritization," the official said. This could be Russia refocusing its strategic goals or trying to gain leverage for talks, the official said.

Meanwhile, in the hard-hit city of Mariupol in southern Ukraine, "the Ukrainians are slugging it out" and "keeping the Russians at bay," the official said.

In Kyiv, the situation is static, the official said. Russian troops have stopped making advances toward the capital city, though they continue using their long-range missile fires, the official said.

"We continue to see Ukrainians defend the city and try to push Russians back," the official said.

-ABC News' Luis Martinez