Deputy Secretary of Defense Patrick Shanahan hosts an honor cordon for Bosnia and Herzegovina's Minister of Defense Marina Pendes at the Pentagon on Sept. 12, 2017. Department of Defense photo

WASHINGTON — President Donald Trump plans to nominate acting Secretary of Defense Patrick Shanahan to formally take over the top spot at the Pentagon, the president's spokeswoman said Thursday. Shanahan, a former longtime executive at aerospace giant Boeing, needs Senate confirmation for the post most recently held by James Mattis. "Based upon his outstanding service to the Country and his demonstrated ability, President Trump intends to nominated Patrick M. Shanahan to be the Secretary of Defense," White House press secretary Sarah Huckabee Sanders wrote in a tweet. "Acting Secretary Shanahan has proven over the last several months that he is beyond qualified to lead the Department of Defense, and he will continue to do an excellent job," Sanders wrote.

President Donald Trump listens next to Acting U.S. Defense Secretary Patrick Shanahan during a Cabinet meeting on day 12 of the partial U.S. government shutdown at the White House in Washington, U.S., January 2, 2019. Jim Young | Reuters

Shanahan, 56, had no prior experience either in the military or in foreign policy before he became the deputy Defense secretary in 2017. "I am honored by today's announcement of President Trump's intent to nominate," he said in a prepared statement. "If confirmed by the Senate, I will continue the aggressive implementation of our National Defense Strategy." "I remain committed to modernizing the force so our remarkable Soldiers, Sailors, Airmen, and Marines have everything they need to keep our military lethal and our country safe." In the wake of the announcement, Shanahan told reporters at the Pentagon that he learned of Trump's intent to nominate him Thursday afternoon at the White House.

"The biggest challenge is going to be balancing it all," Shanahan told reporters. "I'd say, for me, it's about practicing selectful neglect so that we can stay focused on the future but not ignore a lot of the emerging really important issues that pop day to day that you don't plan for." Shanahan's views on America's role in the world have been shaped by decades in the private sector. Before coming to the Pentagon, Shanahan spent just over 30 years at Boeing, where he oversaw the management of profit and loss for the 737, 747, 767, 777 and 787 programs. In 2017, he left the company to become the 33rd deputy secretary of Defense, a role that oversees the Pentagon's colossal $700 billion budget. The nomination follows the end of a monthlong ethics investigation into Shanahan, conducted by the Defense Department's inspector general. The IG's office examined whether Shanahan had taken any actions in his official capacity to benefit Boeing, and it ultimately determined that he had not. Shanahan ascended to the acting role in the wake of Mattis' shocking resignation in December.

James Mattis, U.S. Secretary of Defense, right, and Patrick Shanahan, Deputy Secretary of Defense, wait outside the Pentagon before an event in Washington, D.C., on Thursday, Aug. 9, 2018. Andrew Harrer | Bloomberg via Getty Images