History. 5 of 5: no tariff decision inside six months (Brazil 1993, China 1994, Paraguay 1998, Ukraine 2001, Ukraine 2013). In Ukraine 2001 the US took away duty-free access on day 143. If that is treated as tariffs, it is 4 of 5.
Hunch. In December 2025 this same US trade office closed its China chips investigation with a tariff that started at 0%, a cheap step that would count here.
The 29 November market resolves YES if by the end of that day, Washington time, neither the US trade office nor the president has announced a decision to put tariffs on Vietnam in this investigation, so an extension, a deal, no penalty, a penalty that is not a tariff, a proposal of tariffs with no decision on them or silence is YES, while a decision is NO even if the tariffs start later or start at 0%. The date of the action counts, not the date of publication, with USTR releases and the Federal Register first, confirmed by Reuters, read through The Straits Times if Reuters does not open, and Reuters and AP as backup.
We looked for cases where US law forced the trade office to open an investigation, because it had just named that country a priority foreign country. We checked what it decided in the first six months. We found five such investigations from 1993 to 2013: Brazil, China, Paraguay and Ukraine twice.