He trembled with emotion and seemed close to tears as he described how six Indian soldiers had been tortured and mutilated in Pakistani Kashmir before being killed. "These soldiers were tortured and subjected to torture repeatedly," he told a press conference in Delhi. "The condition of the bodies makes it clear that all injuries were ante-mortem, and deaths were caused by torture.
"This is not simply a breach of established norms, it is a civilisational crime against all humanity, a return to barbarous medievalism," he went on. "We demand the perpetrators be brought to justice. I feel as if I have been personally violated. The dignity of every Indian soldier has been violated."
Mr Singh and his Pakistani counterpart, Sartaj Aziz, were to hold talks yesterday that could lower the temperature in Kashmir's "near war", which has cost several hundred lives in five weeks. But the clouds of more general war are gathering over India and Pakistan.
The Indo-Pak relations have plummeted to a new low after the return of the tortured and mutilated bodies on Thursday. The six soldiers had been part of a patrol ambushed on or soon after 14 May. Some had eyes gouged out, others had genitals severed or skulls smashed. Old Indian soldiers said barbaric treatment of prisoners has long been traditional among the tribes in the north of Pakistan, where wives have been known to flay prisoners alive.
Many of the guerrillas who infiltrated the Indian side of the Line of Control (LoC), which is Kashmir's de facto border, are believed to be ethnic Pathan tribesmen from Afghanistan.
The macabre mutilations may have a simple explanation. The handover of the remains, on the eve of the Pakistani Foreign Minister's visit and a week after Indian pathologists say the men were killed, suggests someone in what Jaswant Singh calls "the Pakistani establishment" wants to torpedo the talks and goad India into escalating the conflict.
Indians believe the fighting was a Pakistani army initiative. A respected analyst, Saeed Naqvi, wrote in the Indian Express yesterday that the Kargil operation might have been launched soon after the Indian and Pakistani prime ministers had talks about burying the hatchet, in New York, back in September.
For peace to break out would always be a problem for Pakistan's armed forces, which swallow 25 per cent of GDP. "That is when the army saw the writing on the wall," Mr Naqvi writes. The timing of the body handover fuels the army conspiracy theory.
The latest outbreak began on 5 May when India's 121 Brigade sent a six- man patrol along the LoC at 18,000ft in the rugged, treeless Ladakh mountains, to check whether the snow had retreated enough for the summer positions to be re- occupied.
But all six vanished. When a second patrol went out to search, two died covering their comrades' retreat and India discovered hundreds of guerrillas had established fortified positions deep inside the Indian border, on the peaks of the hills, with sophisticated equipment and supply lines back to Pakistan-controlled Kashmir.
India started air strikes on 19 May to destroy these positions, and MiGs attack almost daily. The Indians say the guerrillas include Pakistan army regulars as well as mercenaries.
Sartaj Aziz's visit was proposed by Pakistan's Prime Minister, Nawaz Sharif, on the phone to the Indian Prime Minister, Atal Behari Vajpayee. Yesterday, Jaswant Singh said: "India is committed to the dialogue [with Pakistan] because we are the initiators of the dialogue ... We continue to believe that in the ultimate, peace must prevail between these two lands."
Mr Singh's demands for Mr Aziz are "re-establishment of the status quo ante", and that "the perpetrators [of atrocities against Indian soldiers] be brought to justice".
He said Pakistan should pull back from "this ill-judged adventure". But what if the Pakistanis don't, a journalist asked? "Time will tell," said Mr Singh.