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(NEW YORK) — Russian President Vladimir Putin’s “special military operation” into neighboring Ukraine began on Feb. 24, with Russian forces invading from Belarus, to the north, and Russia, to the east. Ukrainian troops have offered “stiff resistance,” according to U.S. officials.

The Russian military has since launched a full-scale ground offensive in eastern Ukraine’s disputed Donbas region, capturing the strategic port city of Mariupol and securing a coastal corridor to the Moscow-annexed Crimean Peninsula.

Here’s how the news is developing. All times Eastern:

Sep 21, 9:32 AM EDT
White House reacts to Putin’s partial military mobilization

Russian President Vladimir Putin’s partial military mobilization for his ongoing war in neighboring Ukraine is “definitely a sign that he’s struggling,” according to the White House’s National Security Council spokesman John Kirby.

“And we know that,” Kirby told ABC News’ George Stephanopoulos during an interview Wednesday on Good Morning America.

“[Putin] has suffered tens of thousands of casualties. He has terrible morale, unit cohesion on the battlefield, command and control has still not been solved. He’s got desertion problems and he’s forcing the wounded back into the fight,” Kirby added. “So clearly manpower’s a problem for him, he feels like he’s on his back foot, particularly in that northeast area of the Donbas.”

Some 300,000 Russian reservists are expected to be conscripted, which Kirby noted is “a lot.”

“That’s almost twice as much as [Putin] committed to the war back in February,” he said.

Kirby said Putin’s latest nuclear threats are “typical” but something the United States and its allies still take “seriously.”

“We always have to take this kind of rhetoric seriously,” he added. “It’s irresponsible rhetoric for a nuclear power to talk that way, but it’s not atypical for how he’s been talking the last seven months and we take it seriously. We are monitoring as best we can their strategic posture so that if we have to, we can alter ours. We’ve seen no indication that that’s required right now.”

And if Russia does use nuclear weapons, “there will be severe consequences,” according to Kirby.

While Moscow appears poised to annex Russian-held regions in Ukraine and attempt to politically legitimize it with sham referendums in the coming days and weeks, Kirby said the United States will still consider those areas Ukrainian territory.

“We’re going to continue to support Ukraine with security systems and other financial aid, as the president said, for as long as it takes,” he added. “That is Ukrainian territory. It doesn’t matter what sham referendum they put in place or what vote they hold, it is still Ukrainian territory.”

Sep 21, 7:47 AM EDT
Putin orders partial mobilization, says he won’t ‘bluff’ on nukes

Russian President Vladimir Putin has ordered a partial mobilization of reservists in Russia, in an apparent admission that his war in neighboring Ukraine isn’t going according to plan.

In a seven-minute televised address to the nation that aired on Wednesday morning, Putin announced the start of the mobilization — the first in Russia since World War II. The measure is expected to draft more than 300,000 Russian citizens with military experience, according to Russian Defense Minister Sergey Shoigu.

The move comes as Moscow is poised to annex all the regions it occupies in Ukraine in the coming weeks, with plans to hold sham referendums this weekend to legitimize its actions. By declaring those areas officially Russian territory, Putin is also threatening that any continued efforts by Ukraine to retake them will be seen as a direct attack on Russia. In his speech Wednesday, the Russian leader raised the specter of using nuclear weapons if Ukraine continues to try to liberate the occupied regions.

“In the event of a threat to the territorial integrity to our country, for the protection of Russia and our people, we of course will use all means in our possession,” Putin said. “This is not a bluff.”

“Those who are trying to blackmail us with nuclear weapons should know that the wind can turn in their direction,” he added.

It’s an attempt to regain the initiative after disastrous setbacks in Russia’s war against Ukraine.

Russia has been suffering severe manpower shortages in Ukraine after months of heavy losses, mainly because the Kremlin has pretended it is fighting not a war but a “special military operation.” That, in part, allowed Ukraine’s spectacular counteroffensive in the country’s northeast two weeks ago, which led to the collapse of Russia’s frontline there.

Military experts and Russian commentators themselves had acknowledged that without a mobilization, Moscow is not capable of anymore offensive operations in Ukraine and in the longterm might well be unable to even hold the territory it has already taken.

Putin has balked at ordering a mobilization, until now, because of the huge political risks it carries for him at home. Russians have proved relatively supportive of the war while they have not been ordered to fight it, but this carries much bigger risks now of domestic unrest. It will bring up dangerous memories of the Soviet disaster in Afghanistan and Chechnya.

Yet Putin has clearly decided he must take the risk, with losing the war in Ukraine seen as an existential danger to his regime.

The mobilization order has profound implications for not just Russia and Ukraine, but also for Europe and the United States. It means Putin is expanding the war in Ukraine even further, ready to throw hundreds of thousands more people into it — making the fight harder again for Ukraine, while also raising the threat of nuclear strikes on it. And at home, Putin is going to enter uncharted waters.

Sep 20, 3:50 PM EDT
US and Ukraine bolster efforts to prosecute Russia for war crimes

U.S. Attorney General Merrick Garland met Tuesday with Ukrainian Prosecutor General Andriy Kostin and signed a memorandum of understanding to strengthen their investigative partnership in pursuing prosecutions against Russians accused of committing war crimes in Ukraine.

“America and the world have seen the horrific images and the heart-wrenching reports of the brutality and death caused by the unjust Russian invasion of Ukraine,” Garland said following the meeting at the Department of Justice in Washington.

Garland said the DOJ’s War Crimes Accountability Team has provided Ukraine with a “wide variety” of technical assistance on criminal cases, including collecting evidence and forensic analysis.

The memorandum of understanding, Garland said, will allow the two countries to “work more expeditiously and efficiently” in their investigations of Russian war crimes.

Kostin also delivered somber remarks on war crimes uncovered by Ukrainian investigators since the start of the Russia’s invasion. He said that two hours before his meeting with Garland, a prosecutor in the Kharkiv region of Ukraine informed him of a village “where about 100 graves” were just discovered.

“This place is not safe at the moment since it needs de-mining,” Kostin said. “But this is a new example of mass atrocities by the aggressor. This is a sign that Russia uses not only prohibited means and methods of warfare, but this is a clear and intentional policy of Russia.”

-ABC News’ Alexander Mallin

Sep 20, 2:49 PM EDT
Ukraine conflict could increase food prices, food insecurity: Study

The impact on crop production due to Russia’s invasion of Ukraine will likely continue to increase global food prices and food insecurity, though not as much as initially feared, according to a new study.

The price of corn and wheat are expected to increase by 4.6% and 7.2%, respectively, and crops such as barley, rice, soybeans and sunflower are also anticipated to rise, according to a study from Indiana University published this week in Nature Food.

Nations with current existing food insecurity will be most impacted by the conflict, according to the study.

Other countries, including Brazil, have stepped up their production to fill the gap left by the lack of exports coming out of the region, offsetting some of the impacts on world food prices and food insecurity, the study found. Clearing more land and vegetation to grow crops could increase deforestation and carbon emissions, the study said.

-ABC News’ Tracy Wholf

Sep 20, 2:35 PM EDT
White House slams referendums in Russia-backed regions of Ukraine

U.S. national security adviser Jake Sullivan said referendums planned for this week in Russia-backed areas of eastern and southern Ukraine are a “sham.”

“Russia is throwing together sham referendums on three days notice as they continue to lose ground on the battlefield and as more world leaders have distanced themselves from Russia on the public stage,” Sullivan said in a briefing Tuesday at the White House.

He also slammed legislation being pushed through the Russian parliament to lay the ground for a general mobilization of men aged 17-27 as “scraping for personnel to throw into the fight.”

“These are not the actions of a confident country. These are not acts of strength, quite the opposite,” Sullivan said. “We reject Russia’s actions unequivocally.”

-ABC News’ Ben Gittleson

Sep 20, 12:24 PM EDT
Kremlin says referendums to be held in separatist regions of Ukraine

The Kremlin made a series of dramatic announcements Tuesday, signaling its response to its failing military campaign in Ukraine.

The Kremlin said referendums will be held later this week in Russian-backed regions of eastern and southern Ukraine for people to vote on whether to join Russia.

Dmytro Kuleba, the Ukrainian minister of foreign affairs, called the proposed vote “sham referendums” in a post on Twitter.

“Russia has been and remains an aggressor illegally occupying parts of Ukrainian land,” Kuleba said. “Ukraine has every right to liberate its territories and will keep liberating them whatever Russia has to say.”

Depending on the results of the referendums, which critics say is a foregone conclusion, Russia will suddenly consider territory it has occupied in Ukraine as its own.

Meanwhile, legislation is being rushed through the Russian parliament, laying the ground for a general mobilization of men aged 17-27, an age range that could be expanded.

Russian state media reported that Russian President Vladimir Putin and his minister of defense will address the nation Tuesday night.

According to a Moscow-based military analyst, even parts of Ukraine’s eastern Donbas, which are not currently controlled by Russian forces, will be considered Russian territory.

After its apparently successful offensive in northeastern Ukraine, the Ukranian military now appears to be pushing further east and is contesting areas of the eastern Donbas region.

In a highly symbolic moment, Ukrainian forces claim they have retaken a village in Luhansk, in the northern part of the Donbas, an area the Kremlin took control of in July.

Sep 18, 4:01 PM EDT
Zelenskyy says preparation underway to liberate all of Ukraine

Ukrainian President Volodymyr Zelenskyy said in his nightly address Sunday that he interpreted a lull in fighting after a series of victories by his country’s military forces as preparation for the liberation of all of Ukraine.

“Maybe now it seems to some of you that after a series of victories, we have a certain lull,” Zelenskyy said.

He went on to say, “this is not a lull. This is preparation for the next series. To the next series of words that are very important to us and must sound. Because Ukraine must be free … all of it.”

Ukrainian troops made good on Zelenskyy’s call to take back lands claimed by Russian forces with an aggressive counteroffensive over the past week in the country’s northeast region.

Ukrainian officials said their forces drove out the Russian in two key areas in the Kharkiv region and are not going to let up.

Sep 18, 1:59 PM EDT
Biden says China not supplying Russia weapons to use in Ukraine

President Joe Biden said in an interview with CBS’ 60 Minutes that it does not appear China is sending weapons to Russia to use in Ukraine.

“Thus far there’s no indication that they’ve put forward weapons or other things that Russia has wanted,” Biden said in the clip from the interview released Sunday.

That’s consistent with the message his administration has repeatedly shared for months. But it doesn’t mean China has stopped helping Russia in other ways, including purchasing Russian oil.

Biden recounted how he had previously told China’s President Xi Jinping that if he thought “Americans and others are gonna continue to invest in China based on your violating the sanctions that have been imposed on Russia, I think you’re making a gigantic mistake. But that’s your decision to make.”

Biden also said he does not think there’s currently a “new, more complicated cold war” with China, as the interviewer, Scott Pelley, put it.

-ABC News’ Ben Gittleson

Sep 18, 12:06 PM EDT
‘True face of aggression’: Ukrainian ambassador condemns Russia over mass grave

Ukraine’s ambassador to the U.S., Oksana Markarova, accused Russia on Sunday of committing “war crimes of massive proportions” after a mass grave was discovered in Ukraine.

“It’s tortures, rapes, killings. War crimes of a massive proportions,” Markarova claimed in an interview with ABC “This Week” co-anchor Jonathan Karl. “That’s why we need to liberate the whole territory of Ukraine as soon as possible because clearly Russians are targeting all Ukrainians. Whole families. Children. So, there is no war logic in all of this. It’s simply terrorizing and committing genocide against Ukrainians.”

Ukrainian President Volodymyr Zelenskyy said in an address on Thursday that a mass grave was found in the recently recaptured territory of Izyum. Over 400 bodies could be buried in the site, according to Ukrainian officials.

Markarova said the majority of the bodies recovered from the site are Ukrainian, including entire families. She also said most of the remains showed “clear signs of torture.”

She said an investigation of the mass grave is underway and that with the assistance of the United States her country is continuing to prepare national and international criminal cases against Russia.

Russia has repeatedly denied targeting civilians, despite evidence otherwise.

“It’s so important for everyone to see the true face of this aggression and terrorist attack Russia is waging,” Markarova said.

-ABC News’ Kelly Livingston

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