Pakistan, May 11 -- How does a country rebuild a relationship after half a century of suspicion and rancour? The question resonated in Dhaka this week as Interior Minister Mohsin Naqvi sat across from Bangladesh's new minister of state for foreign affairs. As official communiques put it, the two sides saw "vast opportunities for investment." In another season, such platitudes might have passed as diplomatic boilerplate, but the new political setting suggests they carry a rare chance to acquire meaning.

The return of the Bangladesh Nationalist Party (BNP) to power and the ouster of Sheikh Hasina have substantially loosened Dhaka's foreign policy orbit, and Pakistan is trying to find a respectful way back into a relationship that was froze...