Russia-Ukraine updates: 2 US veterans who joined Ukrainian forces missing

Pentagon spokesman John Kirby is blasting Russian President Vladimir Putin's comments at a Victory Day parade in Moscow.

Victory Day is a national holiday in Russia commemorating the Soviet Union's defeat of the Nazis in World War II. Putin said at the parade Monday about the Ukrainian invasion: "You are fighting for the motherland, for its future, so that no one forgets the lessons of the Second World War."

Kirby said that Putin "talked about this being a justified military operation. It's not."

Kirby said diplomatic options remained on the table and Ukraine posed no military threat.

"He said it was timely, that it needed to happen now. No ... he had plenty of options available to him," Kirby said.

He called Putin's comments that Russia was ridding Ukraine of Nazis "a ridiculous claim."

"What we should have heard was plans for how he's going to end the war, how he's going to move his forces out of Ukraine, and how he's going to finally respect Ukraine as a sovereign state, and a nation that bordered his, a nation that posed absolutely zero threat," Kirby said.

-ABC News' Luis Martinez

Tens of thousands of Russians marched in processions through major cities on Monday for an event called the Immortal Regiment -- meant to commemorate relatives who fought and died in World War II. But the marches were also co-opted by the Kremlin to support the Ukrainian invasion.

Many Russians believe the Kremlin's false narrative that Russia is justified in fighting in Ukraine. Some said Russian forces are now repeating the same feats as their ancestors and vehemently backed Russian President Vladimir Putin.

Two women told ABC News that "Kyiv is Russia" originally, adding, “We are winning and we will win."

Russian forces remain stalled in multiple parts of Ukraine, according to a senior U.S. defense official.

The Russians are only making incremental progress in the northern Donbas region "because the Ukrainians keep pushing them back and keep fighting them back," the official said.

The official described Russian movements in southern Ukraine as "stalled" with "virtually no progress."

In Kharkiv, the Ukrainians are continuing to push Russian forces east of the city.

"The Ukrainians are actually pushing them east into the northern Donbas," the official said. "They're not been able to go through or around Kharkiv right now."

U.S.-supplied howitzers are already coming into play for the Ukrainians. Eighty-five of the 90 American-made howitzers are now inside of Ukraine, along with significant amounts of ammunition sent by the U.S., the official said.

"These howitzers are already in the fight," the official said.

-ABC News' Luis Martinez

Ukrainian President Vladimir Zelenskyy released a video message from Kyiv early Monday to mark the World War II victory over Nazi Germany, telling his country that "very soon there will be two Victory Days in Ukraine."

"Today, we celebrate the Day of Victory over Nazism. And we will not give anyone a single piece of our history," Zelenskyy said. "We are proud of our ancestors who, together with other nations in the anti-Hitler coalition, defeated Nazism. And we will not allow anyone to annex this victory, we will not allow it to be appropriated."

"On the Day of Victory over Nazism, we are fighting for a new victory," he added. "The road to it is difficult, but we have no doubt that we will win."

Zelenskyy's remarks came just hours before Russian President Vladimir Putin delivered a patriotic speech in Moscow's Red Square on Monday morning during a military parade for Victory Day, a national holiday in Russia commemorating the Soviet Union's defeat of the Nazis in 1945. Putin defended his invasion of neighboring Ukraine, telling Russian troops: "You are fighting for the motherland, for its future, so that no one forgets the lessons of the Second World War."