Nukes exploding on others territories are not the opening act in world war III. They were the last act in World war II against large civilian population centres and no doubt would have been dropped on Dresden or other German cities had they been available. During the cold war nuclear tests were confined to remote islands and deserts, civilians in the vicinity of these tests suffered the direct long term health effects. The cold war end game saw treaties put in place to reduce the number of nuclear weapons and some of these treaties were broken during the reign of George Bush II whose unwise actions have uncorked the kinetic war in the middle East. You should be well used to Trumps strategy by now, open with a big offer and then roll back in the negotiations with what you really want and both sides can walk away with something from the deal. The United States remains the only country to have ever used nuclear weapons directly against civilians in war. Large scale nuclear weapons only tactical use is in scorched earth policy to deny an advancing enemy use of resources in captured territory, however their primary role is that of weapons of terror used to scare civilian populations into compliance by their own governments. Anyone who thinks nukes act as a deterrent to war learned nothing from the actions of Churchill and Bomber Harris over Germany, not only did the bombing raids not stop the war, they likely extended it by forcing the enemy to disperse their war production over a wider area which only came to a stop when the transport infrastructure got destroyed. The ruling megalomaniacs (Churchill, Hitler, Roosevelt, Stalin, Hirohito, Chiang Kai Shek, Mao Zedong) remained in power, none were successfully overthrown by their own populations as a result of destruction of civilian population centres. Mutually assured destruction only stops the major powers from direct military attacks on each other, it has never stopped nuclear powers engaging in combat via diplomacy (i.e. the UN) or proxy wars that draw in the rest of the world. You see this in Africa (Competition for resources in traditional Western colonies vs China), The Middle East (West vs China competition for resources), The Ukraine (Russian backed kleptocrats Vs Western backed kleptocrats) and the South China Sea (US allies vs China building up bases, with North Korea as Chinas sabre rattling proxy) and thrown into this quagmire the Muslim populations reaction to modernity which sees unification under the Caliphate as the answer.
World War II did not start in 1939, that was the final conflagration in the war, the war was well under way from the mid 1930s most visible in the foreign parities involved in the Spanish civil war (testing weapons and tactics) and the Japanese conquest of Manchuria (with backing for the Chinese from Western powers). Increased military spending and economic sanctions were also a prelude to the final conflagration (1939-1945).
Putin is an insider (ex-KGB) from the Soviet regime, as the leader of a country whose wealth is based on resource extraction, he sees power in terms of territory held and for him land is power. His brand of Russian nationalism seeks to regain the territories of “near Russia” as an antidote to reform of the Russian bureaucracy and dependence on resource extraction. If you compare the Russian and Chinese ruling regimes to the disintegration of socialism in their countries, you can see that the Chinese adopted a sit back and let the people get on with it approach to economic development while they kept power, law and order, their people built their own enterprises and have been very successful, the Russians still have the old Soviet bureaucratic overhead interfering in their citizens lives and now that the price of those resources has fallen in the current cycle and an economic blockade has been enforced, the Russian regime has turned to nationalism as a distraction from it’s lack of reform and are able to play on that paranoia using examples from their history such as invasions of Napoleon and Hilter from the West. In order to cover his back Putin has had to make some cut price deals with the Chinese leadership and long term that is something the Russians will have to deliver on as the Chinese seek to reinvigorate the silk road mainly to get resources out of central Asia. For now Russia and China are mutual allies under the umbrella of the Shanghai Cooperation Organisation.
From what I see Trump has no interest in expanding wars (he also has too many significant domestic enemies to contend with, Putin does not) and is protectionist in outlook, the faction of the government military industrial complex that has backed him also sees the policy pursued by the previous administrations in the middle east and against Russia as fruitless. They see China as the real long term threat to their interests and would prefer to orientate themselves to a policy of containment rather than direct confrontation. Trump also sees countries like Germany, Britain, France and Japan as getting a free ride with subsidised American military protection while at the same time undermining American domestic industries, especially with trade barriers. The EU and US are currently engaged in an undeclared trade war that involves American corporations (Apple, Facebook, Google) versus German corporations (Volkswagen, Duetchebank), under Trumps administration what way do you think this is going to go? All governments seek more tax revenue, and EU based governments with moribund economic growth, high unemployment and huge welfare spending (corporate and social) have hit a wall, they can’t raise taxes much more (Irish water is fundamentally a tax protest) without significant resistance from their own populations and must enter a period of significant reform themselves, the EU which was meant to be a stabilising political force has become the problem for Europeans by preventing any significant reform by bailing them out members and enforced a failed economic doctrine of negative interest rates and bond buying programs to cover the mess. Who is going to buy Irish sovereign debt when they stop? I said months ago if Clinton wins we fight Russia, if Trump wins we fight among ourselves so far that’s the way things are shaping.