US detected Indian nuke test buildup in 1995

In the last months of 1995, US intelligence agencies detected signs of India's nuclear test preparations at Pokhran but the satellite photos that analysts studied were "as clear as mud," according to declassified documents published today.
The set of classified documents released by National Security Archive (NSA) and Nuclear Proliferation International History Project through the mandatory declassification review process, sheds light on the intelligence watch over the Indian test site and the Bill Clinton administration's efforts to head-off a feared test.
Surveillance by US intelligence of the Indian test site at Pokhran was intense.
Declassified e-mails by Arms Control and Disarmament Agency staffers indirectly discuss satellite reconnaissance photography of the test site noting the mysterious rearrangement of cables possibly connecting to a test device, NSA said.

The e-mails provide readers with a sense of the difficulty of analysing satellite photographs of intricate human-made structures.
These documents among other things refers to an August 1996 conversation between the then US Ambassador to India, Frank Wisner, and the then BJP leader and future prime minister Atal Bihari Vajpayee.

According to an embassy message, Vajpayee's "body language" indicated that he "would favour a test."
According to one of these documents, after satellite imagery became clear that India was planning a nuclear test, Wisner warned the Prime Minister's Office that such a move would backfire.
Within a few days, Ambassador Wisner was back in India, where he met with then Prime Minister Narasimha Rao's principal secretary, A N Varma, and showed him a satellite photograph of the test site, and warned that a test would "backfire" against India, the document shows.

In mid-December, when President Clinton called Rao, who had met him in Washington in 1994, the prime minister said that India would act "responsibly", it said.
These documents reveal that the US tried to use Japanese influence to stop India from going ahead with the nuclear test.
According to these documents Prime Minister Narasimha Rao, later decided against the nuclear tests, which were eventually conducted on May 11 and 13, 1998 under Vajpayee's leadership.
The US intelligence establishment was taken by surprise - satellite imagery could have provided early warning but it was not analysed in time.
Moreover, having learned from the 1995 experience (and other earlier episodes), the Indians had hidden their test preparations through a deception campaign, including far better concealment of the activities at Pokhran, NSA said.