The widespread surveillance of Spanish citizens by the US National Security Agency, which caused outrage when it was reported this week, was the product of a collaboration with Spain's intelligence services, according to one Spanish newspaper. Spanish agents not only knew about the work of the NSA but also facilitated it, El Mundo reports. An NSA document entitled Sharing computer network operations cryptologic information with foreign partners" reportedly shows how the US relies on the collaboration of many countries to give it access to intelligence information, including electronic metadata. According to the document seen by El Mundo, the US classifies cooperation with various countries on four different levels. In the first group - "Comprehensive Cooperation" - are the UK, Australia, Canada and New Zealand. The second group - "Focused Cooperation" - of which Spain is a member, includes 19 countries, all of them European, apart from Japan and South Korea. The third group - "Limited cooperation" - consists of countries such as France, Israel, India and Pakistan; while the fourth - "Exceptional Cooperation" - is made up of countries that the US considers to be hostile to its interests. The NSA documents [suggest] the Spanish intelligence services were working hand in hand with the NSA, as were other foreign agencies. But if there was any doubt as to who held the upper hand, the NSA documents make clear that any collaboration was always to serve the needs of protecting American interests.