British Prime Minister Boris Johnson wrote Monday to EU President Donald Tusk reaffirming his desire to conclude a Brexit deal as well as his opposition to the controversial “backstop” on Ireland. The so-called backstop is a mechanism that would keep the UK in EU customs arrangements to prevent a hard border between the British province of Northern Ireland and the Republic of Ireland, an EU member state. Brussels says the backstop is needed as a fallback option to preserve the integrity of European trade and avoid risking a return of sectarian violence in Northern Ireland.