Prime Minister Benjamin Netanyahu of Israel shows an illustration as he describes his concerns over Iran’s nuclear ambitions during an address to the the United Nations General Assembly at U.N. headquarters in 2012. (Richard Drew, File/Associated Press)

This week, Al-Jazeera began reporting on hundreds of secret documents detailing information sharing and cooperation among South Africa’s State Security Agency and intelligence agencies of the United States, Russia, Israel and countries across Africa and Asia. The news service has released little information about its source for the trove of documents. But given how carefully intelligence services treat sharing and liaison with their counterparts, it seems likely that the files were leaked by a person or group affiliated with South Africa’s intelligence service.

The documents and related reporting by Al-Jazeera and the Guardian reveal previously secret details of intelligence agencies’ assessments of other states’ capabilities and intentions (such as contradictions between Israel’s public and private assessments of Iran’s nuclear weapon goals) and provide insight into how and when they cooperate with one another.

The leak is likely to have important implications for the willingness of intelligence agencies to share information in the future. At its heart, intelligence sharing involves the exchange of not simply information, but information that must be kept secret from others. States that share secrets worry that their partners will divulge them, deliberately or inadvertently. The current leak is the latest case, after Wikileaks and the Edward Snowden revelations, where an intelligence “insider” has broken this promise of secrecy.

States’ reaction to this leak will have important consequences for their own security. Greater limits on intelligence sharing might restrict states’ ability to counter transnational terrorist groups and other threats to peace and stability. Leaks by insiders have fast become the biggest challenge to the current intelligence sharing regime. To some extent, these leaks are a public good. They have provided a lot of information about intrusions on civil liberties and human rights by intelligence agencies around the world.

Intelligence agencies are likely to want to share less after this document leak. It makes sense to share only with those whom you trust to keep information secret. Insider leaks may lead states to update their assessments of the trustworthiness of their partners. But limiting sharing to only the most trustworthy states imposes quite serious costs. Only a handful of countries have foreign intelligence services of any size, and none comes close to matching the United States. For smaller countries, this means there are relatively few partners who can provide intelligence on a wide range of issues. After the Wikileaks and Snowden revelations, many commentators suggested that foreign intelligence services would limit sharing with the United States, but it is not clear that this has actually happened.

But cooperating with only the most trustworthy states is not the only way to share intelligence. As I discuss in my book, “International Politics of Intelligence Sharing,” cooperating states can construct institutions and practices that limit their vulnerability to exploitation by their partners. The United States, for example, provides funding and technical support to the intelligence agencies of a number of smaller states. This not only builds partner states’ capacity to develop mutually useful intelligence, but also provides the United States with leverage it can use to punish partners who violate sharing agreements.

This and earlier insider threats suggest it is becoming increasingly difficult for intelligence services to keep their secrets secret. Although we do not yet know the motives of the leaker or leakers in the South African case, many of the previous leakers were unhappy about their governments’ willingness to aggressively exploit their growing capacity to monitor communications, even when doing so threatens civil liberties.

One solution is for governments to be more transparent about how they trade off such rights against their need to collect intelligence. Greater transparency can convince insiders motivated by civil liberties concerns that their governments are being straightforward with the public about what information collection is and is not being undertaken. At first glance, greater transparency would seem to increase the problems that intelligence services face by providing not only their citizens but also their adversaries with insight into their secret activities. The key is to be transparent about what sort of information intelligence agencies are seeking, and keep secret the specific tools and procedures they use to collect this intelligence. Achieving this (difficult) balance will become only more important and valuable as the scale and scope of leaks increases.

James Igoe Walsh is professor of political science at the University of North Carolina at Charlotte. He tweets at @jamesigoewalsh.