India said it attacked terrorist camps just across the border in Pakistan late on Wednesday, the biggest military escalation since a standoff in 1999, as Prime Minister Narendra Modi retaliated for a deadly strike against Indian soldiers earlier this month.

Heavy casualties were inflicted on militants assembled to infiltrate India, Director General of Military Operations Ranbir Singh said in a briefing in New Delhi on Thursday. The operations have ended and no more are planned, he said, without elaborating.

Indian troops entered about 3 kilometers (1.86 miles) into Pakistani territory and attacked three camps, India Today tweeted, without saying where it got the information.

"This is a very significant announcement," Shashank Joshi, a fellow at the Royal United Services Institute in London, said in an e-mail. "India has conducted covert, retaliatory cross-border raids on many occasions in the 1990s and 2000s, but to prominently announce them is a provocative new approach. Depending on how far the Indians penetrated and the nature of the targets, these might also represent much more ambitious operations."

Tensions between the nuclear-armed neighbors, who have fought three wars since 1947, have risen since a Sept. 18 assault on an Indian army camp in the disputed region of Kashmir that India blamed on Pakistan, though Pakistani leaders have denied involvement.

The attack left 18 Indian soldiers dead.

Modi this week canceled a planned visit to Islamabad in November for a regional summit, and is looking at other diplomatic measures to seek to isolate Pakistan.

Pakistan’s army is capable of defending its borders, Prime Minister Nawaz Sharif said on national television following India’s announcement. He condemned firing across the de facto border that he said killed two Pakistani soldiers.

"There has been no surgical strike by India, instead there had been cross-border fire initiated and conducted by India," the Pakistani army said in a statement, calling the claim of surgical strikes an “illusion”. "Pakistan has made it clear that if there is a surgical strike on Pakistani soil, same will be strongly responded."

Read more at Bloomberg.