The letter cites written responses from Kahl from late last month in which he indicated to senators that an article in The Washington Post in March 2017 was the source of his Twitter posts that day in which he discussed what the senators allege are classified details of a National Security Council committee meeting about a U.S. operation in Yemen.
But the article cited by Kahl does not account for all of the sensitive contents of his tweets, the senators wrote.
They also cited additional tweets from Kahl later in 2017 in which they allege he appeared to confirm leaked classified information related to military options in North Korea and later indicated "multiple" officials within the Trump administration had confirmed the information to him.