WASHINGTON — Last month, well before the World Health Organization declared COVID-19 a global pandemic, a little-known unit within the Defense Intelligence Agency had already predicted that the outbreak would reach pandemic proportions.

The warning came from the National Center for Medical Intelligence, a senior defense official told NBC News. The NCMI, as it is known, is an obscure patch of the U.S. spying community that is now in the midst of one of the most important missions in its history. The warning was first reported by Newsweek.

The NCMI is the intelligence community's eyes and ears when it comes to global disease outbreaks. While the CIA also has a medical intelligence unit, current and former officials said, the NCMI, headquartered at Fort Detrick, Maryland, is the clearing ground for classified information and analysis related to the coronavirus outbreak.

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The Trump administration declined a request to tour the facility and interview its leaders. Former officials and outside experts say the NCMI calls upon all sources of intelligence — from communications intercepts to satellite imagery to human source reporting — to seek answers that elude public health authorities, including whether foreign governments are lying about the extent and nature of the disease in their countries. It also combs open sources, such as social media.

"The value that NCMI brings is that it has access to information streams that the World Health Organization does not have, nor does the Centers for Disease Control or anyone else," said Denis Kaufman, a retired senior officer who worked at the NCMI.

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The NCMI employs a multidisciplinary team of virologists, epidemiologists, toxicologists, medical doctors, veterinarians and other experts with extensive operational medical experience from the military services, Kaufman added.

In normal times, the NCMI's primary customer is the U.S. military, which uses the information to monitor potential health threats to its forces abroad. But in the midst of a pandemic, NCMI analysis is likely a fixture in the president's daily intelligence briefing, officials say.

The NCMI would have been monitoring the virus' beginnings in Wuhan, China, including the Chinese government's effort to cover up what was happening, experts say.

"That's kind of their raison d'être — they would definitely want to know and try to find out what foreign governments really know about what is going on," said Jonathan Clemente, a physician who has visited and written about the NCMI.

Now, the NCMI would be gathering information on everything from strains on hospitals in Italy to signs of the virus in Syrian refugee camps.

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Anthony Rizzo, a former NCMI director, told an interviewer in 2013: "Our job was to predict what would be a threat to the United States. What I'm most proud of is having been part of protecting this country from threats that people will never even know we faced." Rizzo declined to comment to NBC News.

A classified document leaked by Edward Snowden and published by The Intercept in 2016 shows that the NCMI teamed up with the National Security Agency, the digital spying behemoth, to gather "medical SIGINT," or signals intelligence, a government term for the fruits of hacking and eavesdropping.

Topics of interest included "SARS in China, cholera in Liberia, and dysentery, polio, and cholera in Iraq," according to a classified internal document leaked by Snowden.

The NSA and its intelligence agency partners researched "the effect of the epidemic on the state security apparatus," media coverage of the disease, the political and economic impacts of its spread and the "impact" of SARS on the "readiness" of China's People's Liberation Army, according to NSA documents about a SARS conference published by The Intercept in 2016.

NBC News has previously reported that the intelligence community has been warning about the risks of a COVID-19-style pandemic for years in annual threat assessments presented to Congress.

The most recent worldwide threat assessment, put out in January 2019 by the Office of the Director of National Intelligence, included language on global health that was more pointed than in previous years.

"We assess that the United States and the world will remain vulnerable to the next flu pandemic or large-scale outbreak of a contagious disease that could lead to massive rates of death and disability, severely affect the world economy, strain international resources, and increase calls on the United States for support," it said.

No public threats hearing has been held in 2020, in part because intelligence officials badly want to avoid speaking truths they know will offend President Donald Trump, multiple current and former officials familiar with the matter told NBC News.

Exactly what the NCMI is now saying about the global risks of coronavirus, the possible economic impacts and the potential death toll is not something the Trump administration is prepared to make public.