The decision followed a monthlong ethics investigation that found that Mr. Shanahan, a former Boeing executive, had not acted improperly in official meetings when discussing military contractors.
WASHINGTON — President Trump will nominate Patrick Shanahan as his second defense secretary on Thursday, trying to cement the acting Pentagon chief against an expected uphill battle with lawmakers and Defense Department officials skeptical of him, White House officials said.
The announcement, in a tweet from Sarah Huckabee Sanders, the White House press secretary, followed a monthlong Pentagon ethics investigation that found that Mr. Shanahan, a former Boeing executive, had not acted improperly in official meetings when discussing military contractors.
But his nomination will most likely fuel criticism among lawmakers and Defense Department officials who believe he does not have enough foreign policy experience to run the largest bureaucracy in the American government, one that oversees national security issues across the world.
Until December, Mr. Shanahan was a little-known Pentagon official who had previously worked at Boeing for 30 years and had served as the deputy defense secretary since the start of the Trump administration. That changed when Defense Secretary Jim Mattis stepped down in protest of Mr. Trump’s policies — including the president’s surprise announcement that American troops would withdraw from Syria.
By contrast, Mr. Shanahan has held the line for Mr. Trump.
As the deputy defense secretary, Mr.
