The chairman of the House Intelligence Committee made a dramatic disclosure Wednesday about intelligence reports showing that American surveillance captured conversations among members of the Donald Trump transition team.

Rep. Devin Nunes said that "the intelligence community incidentally collected information about U.S. citizens involved in the Trump transition." The California Republican added that "details with little or no apparent foreign intelligence value were widely disseminated in intelligence community reporting."

None of this surveillance was related to Russia, he said.

Related: Trump’s Communications Possibly Picked Up By ‘Incidental’ Surveillance, Intel Chair Says

So what does the Intelligence Community mean when it uses the phrase "incidental collection" to talk about capturing conversations involving Americans?

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Even if, as former CIA Chief of Staff Jeremy Bash suggested to NBC News, the information gleaned turns out to be a "nothing burger"?

Any surveillance on American soil, whether of foreigners or Americans, has to be approved by the Foreign Intelligence Surveillance Court, a post-Watergate reform designed to prevent the government from spying without warrants on its citizens. The court is made up of 11 federal judges, and is based in Washington, D.C.

"Incidental collection" occurs when a foreigner under surveillance calls or emails an American, and that conversation is picked up. When foreigners under surveillance discuss an American, that is also considered "incidental collection" of information about the American.

If there is incidental collection of information by or about an American, that information is usually blacked out in any intelligence report that is generated. However, the American’s name and what he or she said, or what was said about him or her, can be "unmasked" if there is evidence of a crime, or if the information is needed to understand the foreign intelligence.

Adm. Mike Rogers, the director of the National Security Agency, testified to Congress this week that 20 people at the agency, including him, have the authority to unmask the American side of an intercepted conversation.

Robert Deitz, a former top lawyer for the CIA and the NSA, told NBC News that the fact that Americans involved in the Trump transition may have been picked up in surveillance of foreigners "in and of itself, doesn’t mean a thing. All it means is that a person on watch is talking to a U.S. person.

Deitz said he thought it was "rather interesting," that more than one person on Trump’s transition team was picked up, because it’s not that common for Americans to be talking to foreign surveillance targets.

Members of Congress have repeatedly asked the NSA and other intelligence agencies how many Americans are captured each year in incidental collection. But the government has responded that it cannot say. One reason it cites is that many of the communications are never examined. The act of counting might cause a greater invasion of privacy than not counting, officials have said.

The lawmakers who have been most concerned about the potential dangers of incidental collection tend to be Democrats, like Sen. Ron Wyden of Oregon, an ardent Trump opponent.