The request came in the form of an internal message at the US National Security Agency (NSA), which asked Sweden's National Defence Radio Establishment (Svenska Försvarets Radioanstalt – FRA) for translation help in the fight against terrorism.
Wilhelm Agrell, a professor of intelligence analysis at Lund University, said the news brings a great deal of political, legal, and ethical problems.
"You can't just brush it away and say 'there are no problems here'. Of course there are problems, and they're huge and tough to manage," he told the TT news agency.
The NSA's message was accessed by Sveriges Television (SVT) after it was among the documents leaked by whistleblower Edward Snowden, and was sent before an April meeting between the US and Swedish authorities.
The European Cryptology Center (ECC), a part of the NSA, was responsible for the request, stating at the time that there was Swedish information that it "could not fully analyze".
The material on the NSA's desk was collected when people travelled from Sweden to fight in conflict zones or to take part in terrorist training.
"It's because they are communicating in Swedish. The primary requirement is help with the language," Agrell explained.
He argued that Sweden has to be careful when analyzing material gathered by other intelligence agencies.
"If people are speaking Swedish, there is a connection to Sweden, and in such cases we are very cautious. But if someone is travelling from Sweden to fight in war zones, then they are becoming part of something that which it is perfectly legitimate to raise the alarm about," he said.
The ethical problems, he argued, arise if actions such as drone strikes were to be carried out based on the translations, as it would mean that Sweden has been a part of the chain of events. This could even raise issues with international law, he added.
Agrell referred to Sweden and the FRA as the "little brother" of the NSA, a sentiment that echoed journalist Glenn Greenwald's recent comments that the US dictates the terms of Swedish surveillance.