Widespread detentions and demolitions of property targeting Muslims in India have provoked concerns that right-wing Hindu nationalists are exploiting last week’s terrorist attack in Kashmir to deepen a campaign of oppression against the country’s largest minority group.

Public anger has swelled after 26 people — all but one of them Hindu tourists — were killed by militants near the town of Pahalgam in the Indian-administered part of Kashmir, a Muslim-majority region. India has said that Pakistan had a supporting hand in the attack, an accusation that Pakistan denies.

India has appeared to be preparing to strike Pakistan militarily in response to the terrorist attack, with Prime Minister Narendra Modi vowing to hunt down the terrorists and “raze” their safe havens. A Pakistani government minister said on Tuesday that Pakistan believed an Indian strike was imminent.

So far, India’s central government has been focused on carrying out a series of punitive measures against Pakistan, including threatening to disrupt the flow of cross-border rivers. But officials and right-wing Hindu groups have intensified harassment of Muslims, which they have framed as a drive against illegal migrants.

In several states run by Mr. Modi’s Bharatiya Janata Party, local officials have used the moment to hound what they call “illegal Bangladeshis” and Rohingya, the Muslim minority who have fled Myanmar. Such labels, including “Pakistani,” are often used to target Muslim migrants from other parts of India.

The killings of Muslims were reported in two states, Uttar Pradesh and Karnataka, with media reports suggesting they were hate crimes.