A senior U.S. defense official said at a Monday press briefing that Russian missiles are "failing to launch" as they are fired into Ukraine.

Russia has fired more than 1,100 missiles since the invasion last month, according to U.S. assessments, but there are indications they have been facing problems with the reliability of precision-guided munitions.

Some Russian missiles are "failing to launch, or they're failing to hit the target, or they're failing to explode on contact," the official said.

Additionally, Russian forces are no closer to Kyiv than they were more than a week ago.

"They haven't achieved anything in terms of what we assessed to be their objectives, which was population centers so that they could occupy and take over Ukraine," the official said.

"They are looking for a chance to gain some momentum – not even regain momentum ... because they never really had it. And that's what's so frustrating for them," the official continued.

The official said most credit for the stalled Russian efforts goes to the Ukrainian forces and citizens, and the leadership of President Volodymyr Zelenskyy.

-ABC News’ Matthew Seyler

A man who survived multiple Nazi concentration camps was killed in the Russian bombardment of Kharkiv, a city in northeastern Ukraine, on Friday, the country’s Foreign Minister Dmytro Kuleba said.

Kuleba announced the news on Twitter Monday, saying 96-year-old Boris Romantchenko died after a “Russian bomb” hit his home.

“Survived Hitler, murdered by Putin,” Kuleba wrote.

Romantchenko survived four Nazi concentration camps: Bergen-Belsen, Buchenwald, Mittelbau-Dora and Peenemünde.

The Buchenwald Memorial Institute issued a statement saying it is “appalled at the news of Boris Romantschenko’s violent death in the war in Ukraine.”

The institute confirmed a projectile hit the multistory building where Romantchenko lived and ignited his flat.

-ABC News’ Luisa Rollenhagen and Christine Theodorou

Secretary of State Antony Blinken condemned Russia while visiting the U.S. Holocaust Museum Monday to tour its Rohingya exhibit.

At the top of his remarks, Blinken discussed the the Russian government’s “unprovoked, brutal war on Ukraine,” including the strike that damaged the Ukrainian Holocaust memorial Babyn Yar.

He also said the Kremlin is falsely claiming to be stopping a genocide in Ukraine, “abusing the term that we reserve for the greatest atrocities, disrespecting every victim of this heinous crime.”

Blinken then pivoted to discuss atrocities elsewhere in the world including China, Ethiopia and Myanmar.

“The day will come when those responsible for these appalling acts will have to answer for them,” he said.

-ABC News’ Conor Finnegan

Pope Francis made a strong anti-war statement Monday as the Russian invasion of Ukraine entered its 26th day.

In a speech in a private meeting at the Vatican with volunteer members of the I Was Thirsty organization, which promotes clean drinking water to poor areas of the world, the pope decried war and the money spent on weapons.

"Why make war on each other for conflicts that we should resolve by talking to each other as men?" he said to the audience in the Clementine Hall.

"Why not rather unite our forces and our resources to fight together the true battles of civilization: the fight against hunger and thirst; the fight against disease and epidemics; the fight against epidemics; the fight against the poverty and slavery of today?" the pope continued. "We must create the consciousness that continuing to spend on weapons dirties the soul, it dirties the heart, it dirties humanity."

It comes just one day after Pope Francis denounced the “repugnant" war against Ukraine as “cruel and sacrilegious inhumanity" during a noontime prayer in St. Peter's Square, although he stopped short of naming Russia as the aggressor.

-ABC News’ Phoebe Natanson

All Russian troops have left the Ukrainian cities of Kyiv and Chernihiv, withdrawing north toward the borders of Belarus and Russia to consolidate before likely redeploying to the Donbas region in eastern Ukraine, a senior U.S. defense official told reporters Wednesday.

But even with the Russians gone, the territory remains treacherous.

"There are some indications that they left behind mines and things like that, so the Ukrainians are being somewhat careful in some areas north of Kyiv as they begin to clear the ground and clear the territory and re-occupy it," the official said.

While the U.S. hasn't yet seen these troops redeploy elsewhere in Ukraine, it'll likely happen soon, according to the official. Ukrainian forces are preparing for a major fight in Donbas, the official said.

The official also said the Pentagon is "monitoring" an apparent nitric acid explosion in Ukraine's Luhansk region, which Russia blamed on Ukraine.

"We've seen the Russians claim that this was a Ukrainian attack on this. We do not believe that is true," the official said. "We do believe that the Russians are responsible, but exactly what they used when they did it, why they did it, what the damage is, we just don't have that level of detail," the official said.

The official also noted that a small number of Ukrainians currently in the U.S. for "professional military education" were pulled aside for a couple days of training on Switchblade drones, which the U.S. is sending overseas as part of its military aid, according to the official.

"Although it's not a very difficult system to operate, we took advantage of having them in the country to give them some rudimentary training on that," the official said.

-ABC News' Matt Seyler