Donald Trump has privately asked cabinet members in recent weeks whether he should replace his director of national intelligence, Tulsi Gabbard, venting frustration that she shielded a former deputy who undercut his rationale for war with Iran, according to two people briefed on the discussions. It is not clear that Trump will actually fire Gabbard over the episode. Currently, there is no standout candidate to take the job, and advisers have cautioned that creating a high-profile vacancy before a successor is ready could cause unhelpful political distractions. But Trump’s discussions mark an ominous development for Gabbard, given the president tends...