President Trump must clarify his position on the South China Sea. Tensions in these waters are rising quickly, with a U.S.-China conflict increasingly likely.

The urgency is real. Secretary of State Mike Pompeo this week dramatically shifted U.S. policy on the South China Sea to describe China’s territorial claims as prima facie unlawful. Seemingly deliberately, Pompeo’s language also provided a legal foundation for conflict, should it occur. This is not to say Pompeo is wrong. China’s claim that the South China Sea is its own private swimming pool is both absurd and strikingly reminiscent of 1930s Japanese imperialism.