As the White House denies that the president's Oval Office meeting with Russian Foreign Minister Sergey Lavrov and envoy Sergey Kislyak caused any national security damage, current and former intelligence officials are weighing in.

One former official familiar with the information at issue told CBS News, "This is serious. Someone might really die over this information." Another source told CBS News that "not only could a person be killed, but ISIS could speed up plots."

Even though the White House insists that sources and methods were not revealed, a source says, "You don't have to specifically reveal the source to compromise the source." Sometimes, by simply revealing the information, a "source can be compromised." The implication here is that the type of information revealed was not widely known. The information Mr. Trump revealed to the Russians came from a U.S. partner and had not been cleared to be shared with the Russians. A former intelligence official says that if another country had done the same thing to the U.S., it would send the message that whoever revealed the information "can't be trusted."

The White House message on this story is that the controversy is overblown. "If it wasn't such a big deal, why rush to notify CIA and NSA," a source pointed out.

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The information the president discussed with the Russian officials in the Oval Office was classified as sensitive compartmented information -- that is, concerning sensitive intelligence sources or methods -- and it had been circulated among select top U.S. intelligence and law enforcement officials for some time, spanning both the Obama and Trump administrations. Former U.S. intelligence officials tell CBS News the Obama administration was guarded about who was aware of the information because it was considered extremely sensitive and, if revealed, could put sources and methods at risk.

CBS News' Andres Triay contributed to this story.