After London’s most recent terror attacks, British Prime Minister Theresa May called on countries to collaborate on internet regulation to prevent terrorism planning online. May criticized online spaces that allow such ideas to breed, and the companies that host them.

May did not identify any companies by name, but she could have been referring to the likes of Google, Twitter and Facebook. In the past, British lawmakers have said these companies offer terrorism a platform. She also might have been referring to smaller companies, like the developers of apps like Telegram, Signal and Wickr, which are favored by terrorist groups. These apps offer encrypted messaging services that allow users to hide communications.

May is not alone in being concerned about attacks on citizens. After her comments on Sunday, U.S. President Donald Trump vowed to work with allies and do whatever it takes to stop the spread of terrorism. He did not, however, specifically mention internet regulation.

Internet companies and other commentators, however, have pushed back against the suggestion that more government regulation is needed, saying weakening everyone’s encryption poses different public dangers. Many have also questioned whether some regulation, like banning encryption, is possible at all.

Because the internet is geographically borderless, nearly any message can have a global audience. Questions about online regulation have persisted for years, especially regarding harmful information. As a law professor who studies the impact of the internet on society, I believe the goal of international collaboration is incredibly complicated, given global history.

Some control is possible

While no one country has control over the internet, it is a common misconception that the internet cannot be regulated. In fact, individual countries can and do exert significant control over the internet within their own borders.

In 2012, for example, the Bashar al-Assad regime shut down the internet for all of Syria. According to Akamai Technologies, an internet monitoring company, the country went entirely offline on Nov. 29, 2012. The internet blackout lasted roughly three days.

China aggressively blocks access to more than 18,000 websites, including Facebook, Google, The New York Times and YouTube. While there are some limited workarounds, the Chinese government regularly targets and eliminates them.

French courts have prohibited the display and sale of Nazi materials online in France by Yahoo’s online auction service. After losing a legal case, Yahoo banned the sale of Nazi memorabilia from its website worldwide, though it denied that the move was in direct response to the court ruling.

Even in the United States, local governments have shut down mobile data and cellphone service during protests. In addition, the United States reportedly either is developing or has developed its own internet “kill switch” for times of national crisis.

International collaboration

These types of regulation efforts aren’t limited to individual governments. Groups of countries have successfully collaborated to pursue common goals online.

The Global Privacy Enforcement Network, for example, is a network of representatives from nearly 50 countries including the United States, Australia, the United Kingdom and Germany. The GPEN works to develop shared enforcement practices related to internet privacy and has reviewed many companies’ online privacy policies. When the GPEN discovers websites or apps that violate a country’s privacy laws, it informs the administrators or developers and encourages them to follow those laws. The group can recommend countries take enforcement action against websites or apps that do not comply.

The European Union, made up of 28 countries, has also worked to regulate harmful messages on the internet. In 2016, the European Commission announced a joint agreement with internet companies Facebook, Microsoft, Twitter and YouTube. Among other things, the companies agreed to create clear and rapid processes for reviewing potentially objectionable information and removing it if need be.

At the UN

In addition, the United Nations has been pursuing general global regulation of the internet. The U.N.‘s first Working Group on Internet Governance was created in 2004 to propose models for global internet regulation.

Unfortunately, the working group has not been able to agree on how to create new transnational bodies with rule-setting or regulatory power over the internet. Each country has different views on the global political issues raised by the internet’s vast reach. While some countries can find common ground, it may be nearly impossible to create a worldwide model that harmonizes all of these perspectives.

The farthest the U.N. has gotten so far has been creating the Internet Governance Forum, which brings together governments, private companies and individuals to address questions about internet regulation. The group has discussed and reported on internet access, human rights and free speech issues. These discussions are an opportunity to exchange experiences and views, but there are no negotiated outcomes, rules or laws that come from the IGF.

Finding widespread common ground on internet-based issues will likely only become more difficult as the U.K. exits from the EU and the U.S. takes increasingly nationalist positions. Even so, the experiences of smaller groups of countries may inform a broader effort as global policies on terrorism shift, and the world’s approach to internet regulation changes with it.

Shontavia Johnson does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.