The Dominican Republic shut all land, air and sea borders with Haiti on Friday in a dispute about construction of a canal on Haitian soil that taps into a shared river, as armed Dominican soldiers patrolled entry points and military planes roared overhead. Flights were canceled and border towns usually teeming with vendors and Haitians crossing daily to work in the Dominican Republic were subdued. It was unclear how long the rare closure of the borders will last, with Dominican President Luis Abinader saying the measure will remain in place “as long as necessary.”