Waltz was among high-ranking members of the administration who accidentally shared plans about a forthcoming U.S. military attack with the editor of the Atlantic magazine on the messaging app.

There is a very real possibility that Trump keeps Marco Rubio as both secretary of state and national security adviser, according to three people familiar with the matter.

Trump's appointment of Rubio to temporarily replace Mike Waltz as national security adviser is the first major leadership shake-up of the nascent administration, but Waltz's removal had been rumored for weeks — ever since he created a Signal group chat and accidentally added a journalist to the conversation where top national security officials shared sensitive military plans.