United States President Barack Obama's four-day visit to India next month, already mired in various complexities, has received a further jolt in the wake of embarrassing disclosures that Washington had prior information about the Mumbai terror attack in 2008 that killed 166 people which it didn't share with Indian agencies.

According to a report by ProPublica, a Manhattan-based website that specializes in "investigative journalism," the US Federal Bureau of Investigation had information as far back as 2005 that David Coleman Headley, 50, an American national who has emerged as a key conspirator in the attacks, was an active militant in the Pakistani terrorist organization Lashkar-e-Taiba.

There has been a strong reaction in India to the disclosures about Headley, with the Ministry of External Affairs planning to "take up the matter with Obama." US officials, in the meantime, have been emphatic that they "regularly provided threat information to Indian officials in 2009 before the attacks in Mumbai." They even assert that the State Department and the FBI had investigated the warnings they received about Headley at the time, but that alone didn't suffice to establish his clear connect with the Lashkar-e-Taiba.

According to Gavin Greenwood, a security specialist with Hong Kong-based risk management consultancy firm Allan & Associates, the fact that information about Headley's Lashkar-e-Taiba connections came from Headley's wife in the wake of a domestic dispute in which she called the FBI could have cast doubt on its veracity, for instance.

"Had we known about the timing and other specifics related to the Mumbai attacks, we would have immediately shared those details with the government of India," Mike Hammer, a spokesman for the National Security Council, was quoted as saying.

Nonetheless, the expose sent the US embassy in India into damage-control. The US ambassador to India, Timothy Roemer, issued a weekend statement that "we are looking into published reports about possible information related to David Headley that goes back before the Mumbai attacks and how such information can be handled."

Official clarifications notwithstanding, the information has clearly angered the Indians. Why, people want to know, did the US not follow up on Headley's wife's leads, more so because Laskar-e-Taiba had already been dubbed as a Foreign Terrorist Organization in 2001? Was it, as many speculate, because it was convenient for the US "to avoid a line of investigation that could establish its key ally Pakistan's involvement in these attacks"?

The revelations also raise prickly questions about the workings of US law enforcement and intelligence agencies. Though the ruling Congress-led UPA government is playing down the impact of the disclosures, external affairs ministry officials admit anonymously that the Headley controversy may well create diplomatic issues. Obama is scheduled to attend a ceremony commemorating the Mumbai attacks during his India trip. In fact he begins his India trip from Mumbai, India's financial capital, followed by Delhi after which he will depart for Indonesia.

Some observers believe the Headley controversy will definitely cast a shadow on Obama's "history-making" visit to the Land of the Mahatma, a person he is said to idolize.

"The overarching narrative of the Headley incident is that the US is hypocritical while professing to be India's 'strategic partner'," said Prabuddha Dasgupta, a political analyst. "Indians will now believe that the US is playing a double game and is not a reliable partner. The leaks also make the Indian intelligence agencies look idiotic."

The expose also raises questions about Washington's selective sharing of terror information with Delhi. "Even if this issue doesn't have any major impact on Obama's visit, it can certainly impact the trust quotient between Indian agencies and their US counterparts," says an MEA official.

Meanwhile, in Washington, there is apprehension that the disclosures will underscore the intelligence-gathering units' seemingly casual manner towards terror prevention. What's worse, the US administration is also being criticized for not detaining Headley until almost a year after the Mumbai attacks because of his association with them.

Headley was held back only when British intelligence confirmed that he was plotting similar attacks with Al Qaida in Europe. By then, tensions between India and neighboring Pakistan, where Lashkar-e-Taiba militants are based, had already reached a boiling point with unsavory geopolitical repercussions.

Disquiet in both camps is hardly surprising considering how critical the US-India partnership is at this juncture. Expectations are high that Obama's visit will help restore the momentum to a relationship that had gone off kilter in the past couple of years. The Indians revere GeorgeW Bush for his efforts to grant India access to nuclear technology and other issues, and they regard Obama as less than cooperative, especially because of his efforts to slow outsourcing by US companies to other countries. Outsourcing is a major foreign exchange earner for India.

Indian officials are upbeat about the imminent easing of restrictions by the US on "dual-use" technology flow to India. They are also hopeful of robust engagement in the arenas of space, energy and trade between the world's largest and the oldest democracies.

It is estimated that the Indian market can facilitate the creation of tens of thousands of jobs in the US, certainly an attractive prospect for an economically-bruised America. There's also a strong buzz that India will ink a contract worth $16 billion for 126 multi-purpose fighter aircraft with US companies.

Against this backdrop, it is hardly surprising that Obama is traveling with a large business contingent of 150 business heads of top US firms. "Anybody who is somebody in US business will be here next month," says an anonymous source from the Federation of Indian Chamber of Commerce & Industry. Amit Mitra, General Secretary FICCI adds that "the Indo-US relation is critical not only for these two nations but for the entire geo-political world".

Given these dynamics, there is understandable concern in both Washington and Delhi that the Headley expose does nothing to disturb the delicate balance between the two nations.

Neeta Lal is a New Delhi-based senior journalist; neetalal@hotmail.com