PM Indira Gandhi may have considered destroying Pakistan's nuclear weapons programme when she returned to office in 1980. Though Ramanna had declined to go into specifics, he had recalled to TOI that in 1983, when he was in Vienna to attend an International Atomic Energy Agency meet, he was "warned" by ex-chairman of the Pakistan Atomic Energy Commission Munir Ahmed Khan that if India hit its nuclear facilities, Pakistan would launch a retaliatory strike at BARC, Trombay, in Mumbai, the heart of India's nuclear weapons programme. Ramanna immediately informed Indira about the dangerous consequences of bombing Pakistan's nuclear establishment and the operation was stopped.
The story goes that when Khan was attending the IAEA meet, he received a classified coded message about India's plans through the Pakistani ex-ambassador to Vienna, Abdul Sattar. That night, Khan invited Ramanna for dinner at the Imperial Hotel and the two arch rivals talked for a while. Then the moment arrived when Khan decided to say why he had suddenly called for the dinner meeting: it was not to exchange pleasantries but to deliver a stiff warning about the retaliatory strike on BARC. In the book 'Nuclear Deception' by Adrian Levy and Catherine Scott-Clark, it is stated that India's plan was code-named 'Osirak Contingency', after the Israeli bombing of the Iraqi nuclear weapons plant at Osirak, 18 miles south of Baghdad, in 1981.According to the book, ex-IAF chief Dilbaug Singh was to have commanded the Pakistani operation and had ordered a Jaguar squadron to practice low-level flying with 2,000-pound bombs - a squadron had been kept on standby at the Jamnagar air force base to carry out the attack at a moment's notice.
How the father of Indian N-bomb stalled strike on Pak nuclear sites - The Times of India