This policy brief examines how Western nations respond to investment by sovereign wealth funds (SWFs). It sets out two polar positions on such investment: that it is an issue of national security, as it presents important dangers for Western countries; or that it is an economic governance issue, in which SWF investment can be beneficial to Western countries or its problems have been greatly exaggerated. The paper then compares the policies of the UK, EU and US towards equity investment in company equities. The EU and UK have treated SWF equity investment as a matter of free trade and movement of capital, and imposed few specific restrictions; indeed, they have often accepted and welcomed SWF equity investment. On the other hand, the US has often seen strong debates about whether SWF investment is a free trade or a national security issue, and has imposed much stronger legislative monitoring and restrictions.