Secretary of State Antony Blinken on Thursday vowed that Russia would be held accountable for its war crimes in Ukraine following atrocities revealed outside of Kyiv.

Russian forces have completely vacated the areas surrounding Kyiv, a senior U.S. defense official confirmed this week. But the remains of more than 400 civilians in the suburb of Bucha were found abandoned on the streets or buried in mass graves – prompting global outrage.  

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Secretary of State Antony Blinken

Secretary of State Antony J. Blinken prepares to address a media conference after a meeting of foreign ministers at NATO headquarters in Brussels, Thursday, April 7, 2022. (AP Photo/Olivier Matthys)

"When it comes to Bucha, the atrocities, the war crimes. Accountability, in and of itself, is absolutely necessary," Blinken said. 

Blinken warned that holding individuals accountable for war crimes can be a lengthy process but said, "one day, one way there will be accountability."

The secretary described some of the horrific events he was informed of following Russia’s withdrawal, including the execution of at least one young man who, along with four others, was forced to kneel in front of 40 people crowded into the town square and then shot in the back of the head. 

A survivor from the incident said one of the Russian soldiers then addressed the crowd and said, "This is dirt. We're here to cleanse you from the dirt."

Blinken then described specific incidents of rape and torture occurring outside of Bucha, along with the execution of Mayor Olga Sukhenko from the town of Motyzhyn – whose body was found, with her hands bound, in a shallow grave alongside her husband and son.  

Russian negotiators said they would remove troops from Kyiv and the northern city of Chernihiv to "increase mutual trust."

But officials have warned this is merely a tactic for Russia to resupply its troops and focus its attention on a "major offensive" in eastern Ukraine. 

WARNING: GRAPHIC IMAGE

WARNING: GRAPHIC IMAGE: A cemetery worker waits in a truck before colleagues start to load the corpses of civilians killed in Bucha, before transporting them to the morgue, on the outskirts of Kyiv, Ukraine, on Wednesday.

WARNING: GRAPHIC IMAGE: A cemetery worker waits in a truck before colleagues start to load the corpses of civilians killed in Bucha, before transporting them to the morgue, on the outskirts of Kyiv, Ukraine, on Wednesday. (AP/Rodrigo Abd)

NATO EXPECTING 'MAJOR OFFENSIVE' FROM PUTIN EASTERN UKRAINE, ALLIANCE PREPARING FOR 'LONG HAUL' WAR

NATO, U.S. and Ukrainian officials have also said the atrocities found in Bucha can be expected across the nation, particularly as Moscow sets its sites on Donbas in eastern Ukraine.

"For every Bucha, there are many more towns Russia has occupied, and more towns it is still occupying. Places where we must assume Russian soldiers are committing more atrocities right now," he added. 

Washington has provided more than $1.7 billion in aid since the invasion began in February and more than $2.4 billion since January 2021. 

The U.S. and NATO pledged Thursday to increase support for Ukraine, but officials have remained mum on what type of weaponry they will send Kyiv. 

Ukrainian Foreign Minister Dmytro Kuleba thanked NATO allies for the support they have provided but appeared frustrated when speaking to reporters, referencing constant obstacles Kyiv has had to jump through to get aid to Ukraine. 

A Ukrainian woman mourns the death of her husband in Bucha.

Tanya Nedashkivs'ka, 57, mourns the death of her husband who was killed in Bucha, Ukraine, Monday, April 4, 2022. (AP Photo/Rodrigo Abd)

UKRAINE MINISTER SAYS 'YOU DON'T UNDERSTAND' PAIN OF BUCHA AS VIDEO SHOWS SHOOTING OF WOUNDED RUSSIAN SOLDIER

"The problem [is] that you always have to break one wall after another. The first wall was ‘We're not going to send you weapons.’ OK, we broke it, no one is saying that anymore," he told reporters from NATO headquarters Thursday. "The next one was, ‘We will send you light weapons, but not heavy weapons.’ We broke this wall as well."

"And now we are again in this situation: When? When will you send this?" he questioned. "We have no time."

NATO Secretary-General Jens Stoltenberg said the alliance has been providing aid to Ukraine since Russia invaded in 2014. But Kuleba argued too little too late. 

"It's a little bit of reluctance, unreadiness to act on time, acting only after tragedies like Bucha occur," he listed. 

The U.S. and NATO allies hit Russia with severe sanctions following the February invasion and President Biden announced this week that the U.S. will again increase its sanctions posture – this time targeting Russian President Vladimir Putin’s adult children.

But Ukrainian officials argue more needs to be done to stop Putin’s "war machine" by dropping all oil sales. 

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"How many children, women, men have to die, innocent lives have to be lost, for you to understand that you cannot allow sanctions fatigue?" Kuleba asked. "As we cannot allow fighting fatigue."

The U.S. pledged to immediately stop all oil purchases from Russia last month. But Europe, which relies on Russia for 40% of its energy needs, said it could not afford to make the same commitment until the end of 2022.