So US politics has lead to many countries questioning their alliances etc .
This from a Swiss author .
Quote.
This brings the scenario of a new nuclear arms race within imaginable reach. If the American nuclear umbrella no longer arches over the country's allies in Europe and in Asia, and if Iran openly becomes a nuclear power without the Gulf states having a guarantee of U.S. protection, then a number of countries will not simply shrug their shoulders at their new vulnerability and susceptibility to blackmail. Rather, they will seek to acquire nuclear deterrence capabilities themselves.
Deterrence as a guarantee of survival
The first movers in such a scenario would be countries that felt highly threatened, and which also had the requisite technical and economic capabilities. In Asia, these countries would include South Korea and Japan, which see themselves as being threatened by North Korea and China. In Europe, the main such countries would be Poland and Ukraine. Poland is increasingly being clearly identified as an enemy by an aggressive neo-imperial Russia, while Ukraine has experienced being attacked by a nuclear superpower after giving up the Soviet nuclear weapons stationed on its territory. If Ukraine had its own nuclear deterrent, this would guarantee its survival.
In such a scenario, Germany would be unlikely to pursue its own nuclear capability immediately, as there are still a number of taboos associated with this. Berlin would probably first try to slip back under the protective umbrella of a nuclear power in some way. France would be the most obvious candidate. However, it is doubtful that France would actually credibly issue such a far-reaching security guarantee for Germany. And from a German perspective, it would also be difficult to imagine becoming so heavily dependent on France. Moreover, if the last barriers to nuclear nonproliferation were to fall everywhere – if Japan and South Korea in Asia were to arm themselves with nuclear weapons, and Poland and Ukraine were also to follow this path – then Germany's inhibitions would also be likely to fall considerably.
At the same time, much would change in the Middle East. With Iran as a de facto nuclear power, and if U.S. allies could no longer depend on a protective American umbrella, Saudi Arabia in particular would be likely to seek its own nuclear-arms capacity. Turkey would also be likely to want to go down this route for reasons of power and status, especially as the loss of the American nuclear umbrella would change that country's balance of power with Russia unfavorably.
Dissolution of the global nuclear order
In Asia, there would then be six nuclear powers instead of four (currently China, North Korea, India and Pakistan), in Europe five or six instead of two or three (currently France, the U.K. and Russia) and in the Middle East four instead of one (Israel). A global balance of terror would then become three regional balances of terror, each with its own rules and risks.