Yet Truschke, a scholar, mom, wife and author of three books, now sometimes needs armed security at public events.

The publication of her first book, in 2016, challenging the predominant perception of 16th- and 17th-century Mughal kings — Muslim rulers who are widely vilified by Hindu nationalists — put a target on her back. Her email was bombarded with hate mail. Her Twitter account was inundated with threats. People wrote letters to news outlets about her.

“It felt like the world exploded at me,” said Truschke, pushing back her dark hair to reveal the salt and pepper streaks that frame her face. “This was my first brush with hate email. I’m sure it would seem like nothing to me now.”

Far-right Hindu nationalism, also referred to as Hindutva, is a political and extremist ideology that advocates for Hindu supremacy and seeks to transform a secular and diverse India into an ethnoreligious Hindu state. Hindu nationalism has been around for over 100 years and was initially inspired by ethnonationalism movements in early 20th-century Europe, including those in Germany and Italy. Champions of Hindutva have viciously targeted religious minorities including Muslims, Christians and Sikhs, and have sought to silence critics such as academics and activists.

Hinduism, the faith, is not Hindutva the far-right movement. But the label Hindu can be categorized as a religious, political or racial identifier depending on who is using it, explained Manan Ahmed, a professor and historian of South Asia at Columbia University. Hindu nationalists, he said, are morphing the religious, political and racial into one identity in order to advance a supremacist, majoritarian agenda.

People impacted by Hindutva in the U.S. say the movement has crept into their hometowns and workplaces, making life more dangerous for them and threatening to make their communities less diverse and tolerant. The ideology has deep ties to white nationalist movements across the globe, and the targets of nationalist groups warn that the impact could be deadly if Hindutva is not addressed and defeated.