Bangladesh, Dec. 23 -- Political unrest in Bangladesh has begun spilling across borders, triggering protests in India and straining already sensitive diplomatic ties between New Delhi and Dhaka. Demonstrations outside the Bangladesh High Commission in Indias capital this week underscored how internal instability in Bangladesh-particularly violence against religious minorities-has taken on regional significance, drawing in global actors including the United Nations and Russia.

The immediate trigger for the protests in New Delhi was the lynching of Dipu Chandra Das, a Hindu man killed in the Bangladeshi city of Mymensingh last week following allegations of blasphemy against Islam. The killing, which has shocked minority communities inside ...