The U.S. should have highlighted Russia’s mass grave plans in the run-up to the invasion of Ukraine in order to rally support and strengthen Kyiv’s ability to defend itself, according to a former defense official. 

"I think [the administration] missed an opportunity to sound the alarm at an earlier stage and in a more clear fashion, that they could have done that in December, as opposed to the weeks immediately prior to the invasion," James Anderson, former deputy undersecretary of defense for policy under President Donald Trump, told Fox News Digital. 

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Ukrainian officials said the bodies of 410 civilians were found in Kyiv-area towns and cities retaken as Russian forces withdrew from the area last week. In Bucha, alone, more than 100 civilians were found buried in mass graves, leading President Biden to call for a war crimes trial over Russia’s actions. 

Radio Free Europe in December first reported on Moscow’s plans to standardize wartime mass grave practices, but it was only last week that those plans took on a new light: The standards apply to the "emergency burial" of fallen soldiers, with a specific size that would hold up to 1,000 bodies, as well as how to arrange the bodies and how to cover them. 

Some experts argued that the size of mass graves "are thinkable only for a nuclear war or a pandemic." Gary Kasparov, former world chess champion and chairman of the Human Rights Foundation, referred to the standardization as one of the "signposts on the way to the apocalypse." 

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The standards went into effect on Feb. 1, 2022, just weeks before the invasion started, but residents in Russia heard about the standardization initiative "in the early days of December." 

Galya Morrell, a Russian and American citizen currently residing in the U.S., told Fox News Digital that she read chats at the time discussing the new standards and how people speculated on the range of reasons to make such a move at the time. 

Morrell said the bulk of speculation related to conspiracy theories, such as the graves serving to bury vaccinated individuals or to cover up cases of Siberian anthrax. Others believed it was a case of corruption meant to redistribute the funeral market. 

But Morrell saw it as a clear sign that Putin meant to go as far as needed in Ukraine – including the use of weapons of mass destruction. Morrell said standards noted that "bodies with a high radiation background would be buried in a specially-designated area." 

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"For me, it was the last drop," Morrell, who was in Siberia at the time, said. "While watching the accumulation of Russian troops on the Ukrainian border, I still had some hopes that this is just a tactical method of diplomacy, this time I thought that such losses, in which digging mass graves for civilian population may be necessary, could only be mean one thing: the use of weapons of mass destruction, whether chemical or nuclear."

Anderson argued that it is hard to draw a line from the mass grave initiative to "what we’re seeing now in Ukraine," and he reiterated the value of using it to raise greater resources for Ukraine months ahead of time. 

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"It could have provided – not that it might have deterred Putin from invading – but it could have provided Ukraine more warning time to prepare itself for the invasion," Anderson said. "It could have provided Congress with an added sense of urgency to provide Ukraine with defensive weaponry in a more timely fashion and in greater volume and numbers." 

Fox News' Brooke Singman contributed to this report.