Washington (CNN)The intelligence behind the US ban on laptops and other electronics is considered so highly classified that CNN, at the request of US government officials, withheld key details from a March 31 story on the travel restrictions.
Inside the US effort to keep laptop bomb intel secret
Some of those details are once again at issue following The Washington Post report Monday night that President Donald Trump shared highly sensitive information with two top Russian diplomats in a meeting at the White House.
The concern, US officials told CNN in late March, was that publishing certain information, including a city where some of the intelligence was collected, could tip off adversaries about the sources and methods used to gather the intelligence.
Over several days, US intelligence officials spent hours on conference calls making specific requests to CNN to withhold certain details of the intelligence information.
Those details included information that Trump reportedly shared in his Oval Office meeting with Russian Foreign Minister Sergey Lavrov and Russian ambassador to the US Sergey Kislyak.
In a narrowly worded denial Monday night, national security adviser H.R. McMaster told reporters that the Post story about the meeting "as reported" was false. Two former officials knowledgeable about the situation confirmed to CNN that the main points of the Post story are accurate.
The White House hasn't denied that the President appears to have let the Russian government in on information so highly sensitive that the US government had previously told CNN that publishing it would endanger lives and destroy intelligence-gathering methods used to keep an eye on terrorist groups.
In tweeting about the matter Tuesday morning, Trump confirmed he shared information but did not say whether any of it was classified.
"As President I wanted to share with Russia (at an openly scheduled W.H. meeting) which I have the absolute right to do, facts pertaining to terrorism and airline flight safety, Humanitarian reasons, plus I want Russia to greatly step up their fight against ISIS & terrorism," Trump tweeted Tuesday morning.
Sharing this information with Russia would be a major concern because it could help the Russians figure out how the US obtained the information. The sensitivity is heightened because the Russians share information closely with the Syrian regime.
CNN first reported that US intelligence and law enforcement agencies believed that ISIS and other terrorist organizations had developed new ways to place explosives in laptops and other electronic devices to evade airport security screening methods.
US intelligence suggested that terrorists had obtained sophisticated airport security equipment that allowed them to test how to effectively conceal explosives in electronic devices, CNN reported at the time.
To address the specific concerns of US intelligence, the CNN report didn't say that advances in ISIS bomb-making expertise was the primary driver behind the changes in airline security rules.
US officials told CNN that the US intelligence on the laptop bombs was shared with the so-called "Five Eyes" countries, the term used for the five anglophone nations -- the US, UK, Canada, Australia and New Zealand -- whose intelligence agencies coordinate closely.
But aspects of the intelligence include information from allies in the region -- outside the Five Eyes -- and there's a protocol that includes seeking permission before sharing such information with Russia.
The White House, in response to reporters' questions, has only minimized the nature of the information, suggesting some of it could be easily found on the Internet.