MEXICO CITY — Countries don’t disappear, it has been said, but sometimes they do encounter perfect storms. These do not threaten their existence, yet they can represent major challenges to their welfare and integrity. Mexico may be on the verge of such a perfect storm as it enters a new year fraught with multiple perils and few opportunities.

Three dark clouds threaten Mexico’s future in 2018: Donald Trump’s tax overhaul, the possible end of Nafta and a presidential election that may introduce an era of turmoil and uncertainty for the economy and Mexican society at large.

The first threat has little to do with Mexico’s policies or control of its destiny. Whatever one thinks of the new tax regime in the United States, there is little question that it belongs strictly to the American domestic policy realm, unlike immigration policy, which has been the subject of several agreements between the United States and, among others, Mexico and Cuba.

Nonetheless, with regard to tax policy, the problem for the United States’ neighbors lies in the consequences it may have on their domestic economies. This is a typical internal economic policy issue of the United States, like raising or lowering interest rates, with major international repercussions. For Mexico, it is quite likely, economists say, that Trump’s tax reform entails three significant downsides.