President-elect Donald Trump has chosen retired Marine Gen. James Mattis to lead the Defense Department, he announced Thursday in Ohio.

The pick was first reported by The Washington Post and CNN , which cited anonymous sources, but Trump spokesman Jason Miller later tweeted that no decision has been made yet for the open post.

Trump said Mattis appointment would be announced Monday, and told a rally crowd: Dont tell anyone.

I want to save the suspense for next week. I wont tell you. I refuse to tell you, he said.

The 66-year old general, whose nicknames include Mad Dog and Warrior Monk, was unexpectedly replaced as head of U.S. Central Command in 2013 amid disagreements with the Obama administration over his aggressive posture toward Iran. According to Foreign Policy , Mattis pushed the civilians so hard on considering the second- and third-order consequences of military action against the Iranian regime.