Press TV - The acting secretary of US Department of Defense is quitting at a time the United States is escalating tensions in the Middle East.

US President Donald Trump announced on Twitter Tuesday that Patrick Shanahan has withdrawn from consideration for the post "so that he can devote more time to his family."

A 2011 incident involving Shanahan�s son beating his mother with a baseball bat and fracturing her skull was earlier cited as a potential reason for the move.

�Acting Secretary of Defense Patrick Shanahan, who has done a wonderful job, has decided not to go forward with his confirmation process so that he can devote more time to his family,� said the US president.

The FBI has also launched an investigation into Shanahan and his ex-wife�s exchange of assault accusations in 2010.

Shanahan said it was "unfortunate that a painful and deeply personal family situation from long ago is being dredged up and painted in an incomplete and therefore misleading way," adding that he does not want his children "to relive a traumatic chapter in our family's life and reopen wounds we have worked years to heal."

"I would welcome the opportunity to be secretary of defense, but not at the expense of being a good father."

Army Secretary Mark Esper (pictured below) was appointed to oversee the Pentagon.

�I thank Pat for his outstanding service and will be naming Secretary of the Army, Mark Esper, to be the new Acting Secretary of Defense. I know Mark, and have no doubt he will do a fantastic job,� Trump said.

The announcement came at a time that the US was escalating tensions in the Middle East by stepping up threats against Iran, including a Tuesday announcement about deployment of 1,000 additional troops to the region.