India’s Hindu nationalist government on Wednesday won parliamentary approval for a far-reaching citizenship law that critics say undermines the country’s secular constitution by excluding Muslims.

Violence broke out in the ethnically diverse northeast while parliament debated the bill, as protesters against the legislation clashed with police.

It is the third key election promise that Prime Minister Narendra Modi’s government has delivered since he was re-elected in May, re-energizing his nationalist, Hindu support base and drawing attention away from a slackening economy.

Soldiers were deployed in Tripura state and reinforcements put on standby in neighboring Assam, both of which border Bangladesh, where people fear an influx of settlers.

“The bill will take away our rights, language and culture with millions of Bangladeshis getting citizenship,” Gitimoni Dutta, a college student, said at a protest in Assam’s main city of Guwahati.

The Citizenship Amendment Bill seeks to protect besieged minorities in neighboring states by granting Indian nationality to Buddhists, Christians, Hindus, Jains, Parsis and Sikhs who fled Afghanistan, Bangladesh and Pakistan before 2015.