At first glance, Israeli Prime Minister Binyamin Netanyahu could not have a better friend in the White House.

In his first two months in office, President Donald J. Trump authorised US$11 billion in arms sales, signed a swath of executive orders to crack down on criticism of Israel, put universities and student protesters in his crosshairs, and legitimised ethnic cleansing.

Even so, Mr. Trump’s four years in office may not be honeymoon years for US-Israeli relations.