Trump’s Indictment Exposes His Threat to the Republican Brand

For all my adult life, the Republican Party has associated itself with a strong national defense. That still applies today. Before the party gave up on producing a quadrennial platform statement, it highlighted the distinction between the GOP and the Democratic Party, particularly when it comes to spending on domestic entitlement programs, by insisting that preserving robust national-defense capabilities should be the No. 1 priority for all presidential administrations.

The federal indictment unsealed on Friday against Donald Trump suggests that, if the GOP goes all-in on his plans for defense,...