Pakistan, Nov. 4 -- President Donald Trump chose America's midterm election day to announce that Washington would stop providing nearly $4 billion in annual assistance to Israel by December. He claimed to have reached an understanding with Israeli Prime Minister Benjamin Netanyahu months earlier. Neither government has so far produced its terms, but the timing is far too critical to be swept under the rug. With control of Congress hanging in the balance, Israel's place in American politics had become an electoral liability that even Trump could no longer brush aside.

There is, however, a considerable distance between a loud declaration and a change in American law. The existing ten-year arrangement provides $38 billion through fiscal yea...