Is Brazil the target of industrial espionage?
It was not quite the kind of attention Brazilian President Dilma Rousseff wanted to attract to her country's mining and oil riches.
Documents leaked by former US National Security Agency (NSA) contractor Edward Snowden in September have suggested that the NSA spied on Petrobras, Brazil's state oil giant.
The allegations caused uproar in Brazil, and prompted President Rousseff to cancel her state visit to Washington, where she had wanted to showcase Brazil's energy riches to potential investors.
Even though over a month has passed since the allegations were broadcast on Brazil's TV Globo, the United States has so far failed to reassure Brasilia about the aims of its surveillance programme.
Brazil's power house
The report on TV Globo, co-authored by Rio-based US journalist Glenn Greenwald, raised the question whether the NSA might have been engaging in industrial espionage against Brazil.
It is an allegation which has been firmly denied by Washington, but one that has touched a sore spot in Brazil.
Petrobras is Brazil's largest company and a major source of revenue for the government. It is also developing Brazil's massive deepwater oil reserves.
On 21 October, Brazil will auction off the rights to develop the biggest of these new oilfields, Libra, to international companies.
So the allegation that the NSA engaged in industrial espionage - and targeted Petrobras in particular - came at the most sensitive of times.
Friends with differences
But Timothy Edgar, who was the White House director of privacy and civil liberties from 2006 to 2009, believes the rationale for spying on a country such as Brazil could be better explained by the strict rules within which the NSA operates.
"I can tell you that the US does not engage in industrial espionage," he told the BBC.
"If there were security reasons why intelligence was being gathered in Brazil, it would be legitimate if it was done under a framework [of national security].
"If it was for industrial purposes, it would be basically a violation of US policy," he explained.
He says that, in general, the US intelligence agencies' priorities are about preventing international terrorism, curbing the proliferation of weapons of mass destruction, and fighting international drug trafficking.
But information about military and political leaders of other countries - especially those perceived as opponents of the US in the international arena - can also be flagged up as intelligence priorities, according to Mr Edgar.
Despite a recent warming of relations between Washington and Brasilia, many analysts say it would not come as a surprise if Brazil had been included among these priorities.
Brazil has used its strategic assets, including those in the energy sector, to expand its geopolitical sphere of influence and to strengthen its bonds with other emerging powers in the southern hemisphere.
In the process, Brasilia has often gone counter to US interests on issues such as the war in Syria and the containment of Iran's nuclear programme.
Mr Edgar says that from the point of view of intelligence-gathering, spying on Brazil would make sense if there was a security-related reason, a "legitimate intelligence nexus", for example, to understand the energy supplies within the hemisphere.
But it is this "intelligence nexus" which Washington has so far failed to provide.
The US intelligence services remained tight-lipped about their reasons for allegedly monitoring Brazil's electronic communications, including those of Ms Rousseff herself.
Washington's silence further compounded Ms Rousseff's anger prompting her not only to cancel her state visit scheduled for 23 October, but also to deliver a harsh criticism of the US during the United Nations General Assembly last month.
She called the US surveillance programme an attack on the "sovereignty and the rights of [Brazil's] people and businesses".
She also dismissed Washington's explanation that its monitoring of communications was for Brazil's own good, saying emphatically that Brazil "knows how to protect itself!".
President Barack Obama has promised that a current review of NSA procedures will reassure "allies" such as Brazil, by ensuring that intelligence collected by the secret services amounts to "information that's necessary to protect our people".
It is unclear how long the review will take and whether it will reassure Ms Rousseff.
But with Mr Greenwald saying he plans to reveal more information about US surveillance practices in the coming weeks, Ms Rousseff's Washington visit seems unlikely to be rescheduled for the near future.