The whirlwind of UK politics in 2022 saw three prime ministers and four finance ministers, not to mention major new foreign policy challenges like the Ukraine war. However, under the radar, one of the key developments in the machinery of the UK government was the National Security and Investment Act, which was introduced in the first week of the year. Its measures, which beef up the nation’s security regime, are by no means an isolated development internationally. Across much of Europe, and indeed the Western world, policymakers are debating the issue of how best to update their economic regimes in light of new national security challenges: Including technological and geopolitical changes that mean that reforms to public powers in terms of scrutinizing investments may well be needed much more regularly in the future. The central policy challenge is how best to combine a broadly open approach to the international economy, while still having appropriate security safeguards. The US has long been a pioneer on this agenda through the Committee on Foreign Investment in the United States. This is an interagency committee of the US government that was first established by President Gerald Ford in 1975 to study foreign investment. In the 1980s, Congress passed an amendment thatempowered it to reject deals. The committee does not acknowledge which deals are under review and does not publicly announce its findings. It is chaired by the US treasury secretary and includes representatives from 16 US departments and agencies, including defense, state, commerce and homeland security. All US companies proposing involvement in acquisitions with a foreign firm are supposed to voluntarily notify the committee, but it can also review transactions that are not voluntarily submitted. The body’s primary concern in most reviews is that technology or funds from an acquired US business might be transferred to a sanctioned country as a result of being acquired by a foreign firm. The new UK legislation, whose key stakeholders in the government include the business and international trade departments, plus the Home Office and Treasury, has drawn some parallels with the Committee on Foreign Investment in the United States. It represents the biggest shake-up of the UK’s investment screening arrangements in decades, modernizing the government’s powers to investigate and intervene in potentially hostile foreign direct investment. The new UK powers reflect the fact that the country faces continued, broad-ranging hostile activity from actors seeking to compromise its national security and those of its allies. Unless checked, such threats will increase the UK’s vulnerability toisruption, unfair leverage and espionage. London’s screening powers have also been extended to include assets like intellectual property.The 17 defined sensitive sectors are: Advanced materials, advanced robotics, artificial intelligence, civil nuclear, communications, computing hardware, critical suppliers to government, cryptographic authentication, data infrastructure, defense, energy, military and dual-use, quantum technologies, satellite and space technologies, suppliers to the emergency services, synthetic biology, and transport. Under the National Security and Investment Act, the government can impose targeted, proportionate conditions on an acquisition or, if necessary, unwind or block it, although the vast majority of deals will still be able to proceed without delay. The act also grants the government a five-year retrospective window to call in acquisitions in the wider economy that may raise national security concerns. However, these do not apply to acquisitions that took place prior to the legislation’s introduction to Parliament on Nov. 11, 2020, so businesses and investors have certainty about historical deals. This reflects the ambition to provide such stakeholders with the clarity and transparency they need to do business in the UK. One of the first decisions under this legislation came a few weeks ago and concerned the proposed sale of Newport Wafer Fab (the UK’s biggest semiconductor firm) to a Dutch-based technology firm called Nexperia (which is a subsidiary of the Shanghai-listed Wingtech). This was blocked by UK ministers on national security grounds, with Nexperia required to divest 86 percent of the company, leaving it with the 14 percent stake it held before launching a takeover in 2021. Another recent example of the new powers being used was the ministerial decision to order an investment firm, LetterOne Holdings, to sell regional broadband provider Upp. LetterOne, whose investors have included a number of sanctioned Russian businessmen, has been told it must sell 100 percent of Upp, which provides services across the East of England and the East Midlands. The order also compels Upp to complete a full securityaudit of its network ahead of the sale. One year into the new national security regime — while there is still some uncertainty about how it will work in practice — one thing is for sure: Ministers are likely to increasingly use these new powers, given the growing range of geopolitical, economic and technological challenges facing the UK and the wider Western world.