Good writing creates a dialogue between writer and reader, with the imagined reader at moments questioning, criticizing, and sometimes, you hope, assenting.
By assenting to this principle, Mr Clinton has probably made it harder for himself or his successor to pull out of the treaty, as either side may legally do, with six months' notice.
But the Vatican does not accept Pius XII was culpable of assenting to the Holocaust, and - even if it did - it would be impossible to cast blame on a pope whom the current pope has begun moves to beatify.