On Monday evening, the Washington Post reported that Donald Trump allegedly shared highly classified information with Russian officials during a meeting last week. This news has received a substantial amount of attention and has likely led many to wonder if a president has ever shared highly classified information before — or if Trump is the first to do so. While former presidents have certainly shared classified information, the manner in which Trump shared this information and the individuals with whom he shared it make this a somewhat unprecedented scenario.
The Post reported that Trump allegedly shared classified information that was considered "highly sensitive" during a meeting last week with Sergei V. Lavrov, the Russian foreign minister, and Sergey I. Kislyak, the Russian ambassador to the United States. The information allegedly involved Islamic State terrorism tactics, came from a source in the Middle East, and was considered "highly sensitive" intelligence that was not even shared with U.S. allies or many U.S. government officials. In multiple statements, the White House denied the claims made in the Post story, saying via Dina Powell, the deputy national security adviser for strategy, "This story is false. The president only discussed the common threats that both countries faced."
So in a meeting where the US press was forbidden to attend, Trump told Russia our secrets. This is totally normal...NOT— Patrick Tubbs (@Pat1072) May 16, 2017
U.S. presidents choosing to share classified information is not at all a rarity. It is well within the scope of presidential power to share classified information and, indeed, as Slate reported, every president uses U.S. intelligence to move foreign policy goals along. An article in the Atlantic also noted that the Obama and Bush administrations frequently disclosed classified information.
However, while sharing highly classified information is one thing, sharing information that could jeopardize sources and methods for acquiring that information (as Trump allegedly did) is much rarer. However, Slate pointed out that this does happen, although usually in a very pre-planned manner. For example, George W. Bush occasionally invited foreign leaders to classified CIA briefings, though the CIA was notified well in advance and could tailor the briefings accordingly.
What is unique and disconcerting about the Trump situation, however, is the apparent ad-hoc manner in which he revealed the information as well as the fact that he provided the information to an adversary (Russia is not considered an ally to the United States).
In regard to the former point, it is highly unusual for a president to share classified information without a strategic goal in mind and/or without giving intelligence agencies advance notice. As Slate put it, making such a move for no definitive reason is "not normal."
Thus, in sum, it is not unusual for a United States president to share classified information with others. However, the manner in which Trump shared this information, the type of information that was shared, and the individuals with whom he shared this information make the situation highly unprecedented in the history of the Oval Office.