India's Prime Minister Narendra Modi warned Pakistan on Friday to expect a strong response to a suicide attack that killed 44 paramilitary policemen in Kashmir, ratcheting up tension between the nuclear-armed neighbors.
The car bomb attack on a security convoy on Thursday was the worst in decades of insurgency in the disputed region. India said it had "incontrovertible evidence" of Pakistani involvement, a statement quickly rejected by Islamabad.
"We will give a befitting reply, our neighbor will not be allowed to destabilize us," Modi said in a speech, after meeting security advisers to discuss options.
The attack comes months before national elections in India.
The Pakistan-based Islamist militant group Jaish-e-Mohammad (JeM) claimed responsibility soon after a suicide bomber rammed an explosives-laden car into a bus carrying police personnel.
India has for years accused Muslim Pakistan of backing separatist militants in divided Kashmir, which the neighbors both claim in full but rule in part.
Pakistan denies that, saying it only offers political support to the Himalayan region's suppressed Muslim people.
The White House urged Pakistan "to end immediately the support and safe haven provided to all terrorist groups operating on its soil".
Pakistan is due to host peace talks next week between the Afghan Taliban and the United States as part of efforts to seek a political settlement to the Afghan war, but escalating tensions with India could divert Pakistan's attention.
As outrage and demands for revenge flooded Indian social media, Arun Jaitley, one of the most senior figures in the Hindu nationalist-led government, told reporters India would work to ensure the "complete isolation" of Pakistan.
The first step, he said, would include removing most favored nation (MFN) trade privileges that had been accorded to Pakistan - though annual bilateral trade between the countries is barely $2 billion.
The last major attack in Kashmir was in 2016 when Jaish militants raided an Indian army camp, killing 20 soldiers. Weeks later, Modi ordered a surgical strike on suspected militant camps across the border in Pakistan Kashmir.