WASHINGTON (AP) – President Donald Trump has congratulated Gen. Mark Milley on becoming chairman of the Joint Chief of Staff.

President Trump is attending a rainy welcome ceremony for Milley at a military base in Arlington, Virginia. President Trump says he’s always heard that rain on a big event brings luck and tells Milley, “Mark, I think you’re going to be the luckiest general in history.”

The role of the Joint Chiefs chairman is to advise the president, defense secretary and the National Security Council on military issues.

The President also calls Milley his friend and adviser and says he “never had a doubt” about nominating Milley for the position.

Milley, formerly the Army chief of staff, succeeds Marine Gen. Joseph Dunford.

President Trump chose Milley over a candidate favored by former Defense Secretary Jim Mattis.