Recent moves by the European Union and the United Kingdom suggest their dispute over the Northern Ireland protocol could be resolved in the coming weeks, which would not only defuse the threat of a trade war but open the door to greater EU-U.K. cooperation in other areas. In recent months, the United Kingdom has threatened to suspend the Northern Ireland protocol of the Brexit agreement, which establishes customs controls at the Irish Sea, arguing that it causes trade disruptions between Great Britain and Northern Ireland. The European Union has shown willingness to discuss the issue, though it has threatened to impose trade sanctions on the United Kingdom if it makes good on this threat. Both sides have recently made moves to deescalate tensions, indicating a mutual desire to reach a compromise and avoid a trade war. The United Kingdom’s Brexit minister, David Frost, will meet with EU negotiator Maros Sefcovic...