This chapter explores how recent moves by western nations to restrict the involvement of Chinese multinational Huawei in 5G telecoms development could give rise to investor state dispute settlement (ISDS) actions. China has been increasing its outgoing foreign investment and is now a player with global aspirations as evidenced in the Belt and Road Initiative (as well as remaining a major incoming destination for investment); yet Chinese investors have not made much use of ISDS provisions to defend their rights under investment treaties. Investment protections in Bilateral Investment Treaties (BITs) and other multilateral instruments were conceived as tools to protect western multinationals against errant behavior of developing host states. The chapter investigates the degree to which Chinese investors can now use the same protections to protest what they perceive to be discriminatory treatment by western host states on the grounds of national security, using the example of Huawei operations in western states. The chapter contributes to an evolving understanding of investment standards of protection, exceptions to protection on the basis of national security, as well as offering policy insight on the use and future trajectory of ISDS mechanisms in investment treaties.