Indian Prime Minister Narendra Modi’s visit to Bangladesh earlier this month brought with it the formal ratification of a historic land border agreement that finally settles a four-decades-long dispute. Pocked with enclaves and counter-enclaves, the border between India and Bangladesh was a geographical oddity—and a headache for New Delhi and Dhaka. The land swap that Modi agreed to had been in the works for a while; it was actually signed by both governments in 1974, but never ratified. At the cost of ceding some land to Bangladesh, the deal is in keeping with Modi’s agenda to rebuild strategic trust with Dhaka by dropping any perceived “Big Brother” attitude toward its smaller neighbor. Modi made that clear with a slew of other deals to boost trade and ease movement across the border.

Better ties with Bangladesh are vital to India, to secure both the Bay of Bengal and the necessary connectivity for its “Look East” policy aimed at deepening its engagement with Southeast Asia. Recognizing that Modi expended political capital to move ties forward, Bangladeshi Prime Minister Sheikh Hasina reciprocated, agreeing to several transportation deals that had been greeted warily by many in Bangladesh. In return for an Indian promise to redress the current trade imbalance, Bangladesh has also opened its doors to significant Indian industrial investment. If India can move more quickly on delivering a key water-sharing deal to Bangladesh and providing it with military equipment, Dhaka might be persuaded to re-evaluate the nature of its relations with China. Despite overtures from Beijing, Bangladesh, like India, is concerned with China’s damming of rivers in Tibet, which could cool their ties. ...