An executive order says an attack on Qatar would be treated as a threat to the U.S., bolstering security commitments to a key Gulf ally after Israel’s strike on Doha last month.

An executive order says an attack on Qatar would be treated as a threat to the U.S., bolstering security commitments to a key Gulf ally after Israel’s strike on Doha last month.

The White House has said that the United States will treat any armed attack on Qatar as a direct threat and extend security guarantees to the Gulf ally,...