Trump's TikTok attack shows the surprisingly vast power of CFIUS, a decades-old government group that can kill or unwind deals even if none of the companies are American

· President Trump's attack on TikTok has highlighted the extensive, but not-well-understood powers the president has to regulate or block foreign investment in the US.
· The president's order came as a result of a process initiated by the Committee on Foreign Investment in the US, or CFIUS, a group of cabinet officials and...