US Secretary of State Mike Pompeo makes a key trip to Asia-Pacific this week, with a vital stop-off at Thailand’s Association of Southeast Asian Nations foreign minister forum, before heading to Australia. In the Sydney leg this weekend, a bilateral agenda item will be the future of “Five Eyes,” one of the world’s most successful intelligence gathering and sharing partnerships, now under new stress over Chinese participation in 5G telecommunications networks. The origins of Five Eyes stem from the remarkable intelligence relationship that the US and UK enjoyed during the Second World War, which was institutionalized in the 1946 UKUSA Agreement. Canada, Australia and New Zealand, as former UK dominions, began representing themselves in the intelligence pact in the late 1940s and 1950s. To be sure, the US has other intelligence relationships with key allies, from G7 states like France and Germany to Japan. And, in the Middle East, it has intelligence sharing ties with allies including Jordan, Egypt and Turkey. Yet the closest cooperation is among the Five Eyes countries, bonded by decades of strong security, economic, political and cultural ties, with their geographical spread across the globe meaning that members neatly divide intelligence gathering responsibilities by region. The UK, for example, leads on the Middle East and Europe. However, in recent years, the mutual trust that is the foundation of these exchanges has been challenged by several developments, including the Edward Snowden leaks during the Obama administration. Now there are potential divergences over the use of Chinese 5G telecommunications technology, specifically Huawei. Washington and Canberra have been most vociferous in their opposition to Huawei, with both banning the Chinese-headquartered telecoms firm from supplying equipment to their 5G networks. Australia led the way, in 2018, under then-Prime Minister Malcolm Turnbull, when it became the first country to ban Chinese firms from the national 5G network, followed by the US this year. This alignment of stance will be celebrated by Pompeo in Sydney this weekend. He will assert that, almost 70 years since the 1951 ANZUS treaty, US-Australia relations remain strong, built upon a core foundation of shared military and intelligence ties. However, the Fives Eyes powers are not (yet at least) unified on this 5G issue, with New Zealand, Canada and the UK having more nuanced positions. Take the example of London, where, despite security and defense having long been at the core of the special relationship with Washington, tensions surfaced between the Trump team and the former government of Theresa May over Huawei. In the final weeks of the May government, a decision was reached in principle in the UK National Security Council that Huawei would be allowed a limited role in building “non-core” parts of the nation’s 5G network. However, that interim conclusion was leaked, allegedly by then-Defense Secretary Gavin Williamson, who was sacked despite his denials. In recent years, the mutual trust that is the foundation of these exchanges has been challenged by several developments. Andrew Hammond Part of the reason for the sensitivity of this issue is that London allowing even restricted use could create gaps in the intelligence and research shared among the Five Eyes members, given the stance of the US and Australia on the issue, which might potentially lead other members of the alliance to also exclude or severely limit its use. And it is therefore no coincidence that US officials have warned their UK counterparts that it may limit intelligence sharing if they allow Huawei to build part of its 5G high-speed mobile network. This decision, which has now been kicked out to May’s successor Boris Johnson, is a high-stakes diplomatic balancing act for the UK, given its desire to form closer post-Brexit economic ties with China. David Cameron, May and now Johnson have all figured that President Xi Jinping could be in power well into the 2020s, and they and fellow ministers see that there is an opportunity to develop a relationship that could make a significant contribution to UK prosperity for a generation to come. However, the new prime minister has made it a priority to build stronger ties with Donald Trump, including a potential new bilateral trade deal, after the coolness of the latter’s relationship with May. Should there be a breach now between the UK and US-Australia on this issue, intelligence sharing could be curtailed, creating possible gaps in collection, analysis and dissemination, given the UK’s focus on Europe and the Middle East. Meanwhile, London could lose access to information collected by other Five Eyes powers in other areas of the globe, including South America and the Asia-Pacific. While the new UK government of Johnson thinks through these issues, Canada looks likely to postpone a final decision on this thorny issue until after October’s federal election. Meanwhile, New Zealand is looking for a “third way” path. After initially following Australia’s lead, the Government Communications Security Bureau now allows firms to demonstrate that they can mitigate national security concerns before potentially using Huawei equipment in 5G networks. Taken overall, Huawei represents a significant challenge to the future of Five Eyes. Much could now depend upon the stance of Johnson on the issue, which may also help shape the direction of policy in Canada and New Zealand, plus other allied nations outside of Five Eyes.