WASHINGTON — Treasury Secretary Steven Mnuchin inquired about the use of a military plane for his European honeymoon last month, the Treasury Department confirmed on Wednesday, a disclosure that comes as he is already under scrutiny for taking a government plane to Kentucky before viewing the Aug. 21 solar eclipse.

The Treasury Department said Mr. Mnuchin had asked about the military plane so that he would have access to secure communications when he was abroad.

“It is imperative that he have access to secure communications, and it is our practice to consider a wide range of options to ensure he has these capabilities during his travel, including the possible use of military aircraft,” a Treasury spokesman said in a statement.

According to the spokesman, Treasury officials withdrew the request after finding an alternative way to communicate about government matters securely. He noted that Mr. Mnuchin is a member of the National Security Council with responsibility for the Office of Terrorism and Financial Intelligence.