At a speech in India's eastern state of Bihar, Modi folded his hands in prayer in remembrance for the 26 men who were shot and killed in a meadow in the Pahalgam region of Indian Kashmir, exhorting thousands gathered at the venue to do the same.
"We will pursue them to the ends of the earth," Modi said on Thursday, referring to the attackers, without referring to their identities or naming Pakistan.
His comments are, however, bound to further inflame ties between the nuclear-armed rivals after India downgraded ties with Pakistan late on Wednesday, suspending a six-decade old water treaty and closing the only land border crossing between the neighbours.
Pakistan's Power Minister Awais Lekhari called the suspension of the Indus Waters Treaty "an act of water warfare; a cowardly, illegal move".
Police in Indian Kashmir published notices on Thursday naming three suspected militants "involved in" the attack, and announced rewards for information leading to their arrest.
Two of the three suspected militants are Pakistani nationals, the notices said.
They did not say how the men were identified.
India and Pakistan control separate parts of Kashmir and both claim it in full.
Indian foreign ministry chief Vikram Misri said on Wednesday a cabinet committee on security was briefed on the cross-border linkages of the attack, the worst on civilians in the country in nearly two decades.
Misri did not offer any proof of the linkages or provide any more details.
New Delhi would also pull out its defence advisers in Pakistan and reduce staff size at its mission in Islamabad to 30 from 55, Misri said.
India summoned the top diplomat at the Pakistan embassy in New Delhi, local media reported, to give notice that all defence advisers in the Pakistani mission were persona non grata and had a week to leave.
Modi has called for an all-party meeting with opposition parties to brief them on the government's response to the attack.
Dozens of protesters gathered outside the Pakistan embassy in New Delhi's diplomatic enclave on Thursday, shouting slogans and pushing against police barricades.
In Islamabad, Prime Minister Shehbaz Sharif was scheduled to hold a meeting of the National Security Committee to discuss Pakistan's response, Foreign Minister Ishaq Dar said in a post on X.
The Indus treaty, mediated by the World Bank and signed in 1960, regulated the sharing of waters of the Indus River and its tributaries between India and Pakistan.
Diplomatic relations between the two countries were weak even before the latest measures were announced as Pakistan had expelled India's envoy and not posted its own ambassador in New Delhi after India revoked the semi-autonomous status of Kashmir in 2019.
Tuesday's attack is seen as a setback to what Modi and his Hindu nationalist Bharatiya Janata Party have projected as a major achievement in revoking the special status Jammu and Kashmir state enjoyed and bringing peace and development to the long-troubled Muslim-majority region.
India has often accused Islamic Pakistan of involvement in an insurgency in Kashmir, but Islamabad says it only offers diplomatic and moral support to a demand for self-determination.
Tens of thousands of people have been killed in Kashmir since the uprising began in 1989, but it has tapered off in recent years and tourism has surged in the scenic region.
with AP
