As word about India planning a nuclear test spread in 1970, the United States had sent a diplomatic note warning New Delhi that the use of plutonium from the CIRUS reactor, built with Canadian aid, would violate the US-India nuclear cooperation agreement.
"There is a suggestion that Vikram was deeply concerned about the potential fallout of these factors on his beloved space programme," says the book Vikram Sarabhai: A Life written by noted journalist Amrita Shah. In 1970, a view of expression of India's might through a nuclear test or developing a long-range ballistic missile was fast gaining ground.
Then Prime Minister Indira Gandhi had expressed her reservations about a weapons programme but was veering towards conducting a nuclear explosion and had asked Sarabhai, who was chairman of the Atomic Energy Commission, to prepare for it in the mid-1970s.
"What the politicians, bureaucrats and senior scientists at the AEC wanted was a show of India's might. And there was no question of Vikram's stand on that," says the book.
"At the very outset Vikram had made his views on a demonstration clear, going so far as to call it a paper tiger. "Those who knew Vikram well maintain that he would not have disobeyed a direct order from the prime minister," it adds.
The book captures the turmoil that Sarabhai underwent during the period. "Privately, however, Vikram appears to have been torn apart. Kamla (his companion) maintains that he was under tremendous stress at the time," the book says. "Characteristically, however, Vikram concealed his mounting agitation under an appearance of liveliness," it says.
The cost-benefit study for undertaking a peaceful nuclear explosion, commissioned in March 1970, became available in 1971. "The outcome could not have been to his liking; it showed that peaceful nuclear explosives for engineering purposes would be economically viable though weapons might not," it says.
"The pressure was growing. Still, he did not show it outwardly." N Seshagiri of the Tata Institute of Fundamental Research, who was asked to conduct the cost-benefit study, claims that Sarabhai hoped "...that the result might show that the cost of a viable nuclear arsenal could not be justified even if peaceful nuclear explosions were included.
"Some time roughly between June and November of 1971, (his wife) Mrinalini describes him getting up from his sleep suddenly in the middle of the night," the book says.
It was through this raging battle within him that he announced at the Fourth International Conference on Peaceful Uses of Atomic Energy in Geneva in September 1971 that Indian scientists were developing nuclear explosive engineering as a top priority.