WASHINGTON (AP) — Acting Defense Secretary Patrick Shanahan stepped down Tuesday before his formal nomination ever went to the Senate, citing a “painful” family situation that would hurt his children and reopen “wounds we have worked years to heal.”

President Donald Trump announced Shanahan’s departure in a tweet, and said Army Secretary Mark Esper would be the new acting Pentagon chief.

“I believe my continuing in the confirmation process would force my three children to relive a traumatic chapter in our family’s life and reopen wounds we have worked years to heal,” Shanahan said in a statement. “Ultimately, their safety and well-being is my highest priority.”

His withdrawal from one of the most critical positions in the government comes at a time of escalating tensions in the Middle East, a day after the U.S. authorized sending additional troops to the region, and after months of unexplained delays in the confirmation process.

The acting defense secretary did not provide specifics, but court records show a volatile family history around the time of his 2011 divorce. The couple had been married since 1986.

The Pentagon, in a statement, said Esper will take over the job at midnight Sunday. Esper and Shanahan met at length Tuesday to begin transition planning..