American policy toward Somaliland rests on a fiction. Washington treats the territory as if Mogadishu might one day govern it, even though Somaliland has run its own institutions since 1991. President Donald Trump can replace that fiction with a practical partnership by recognizing a state that Somalilanders have already built. The timing is unusually clear. This year marks 35 years since Somaliland restored its sovereignty. The number also reac…