The national-populist forces represented by Trump, Putin, the Brexiteers, Le Pen and others are not fascists. The risk they pose is not the risk of the military taking over and start torturing people and killing members of targeted ethnic groups. The risk they pose is more subtle: it is the risk of manipulating democracy in the name of democracy itself and ordinary people, to result in a society where we start hating each other and stop learning from people from other places. It is important to understand that there are differences between all these movements. For example, Trump is different from most Brexiteers (he is more vulgar, among other things). But it is also instructive to understand what they have in common:
1) They exagerate the positive things and hide the negative things of what is local, and underestimate the good things and overestimate the negative things of what is alien.
2) They think of the important distributive issue as that between communities or territories (usually "nations") and not that between income groups and social classes.
3) They (Trump, the Polish government, Erdogan in Turkey) do their best to attack the division of powers and especially to undermine the role of the media and the judiciary, perhaps because this helps them in their permanent confusion between public and private objectives, including the difficulties of some of their leaders with tax authorities.
4) They need to promote international divisions and to aggravate international tensions or tensions with neighbours and political rivals: they enjoy living in the permanent climate of a "clash of trains."
5) They have a preference for direct democracy: they love referendums or direct communication with voters via social media. They don't like representative or deliberative democracy.
6) They exagerate the size of their political support among the electorate and tend to speak in the name of the people (French far right leader Marine Le Pen or Catalan nationalist Artur Mas) or in the name of ordinary people (Donald Trump). Amartya Sen (a progressive that at a crucial historical juncture has not waivered in his criticism of nationalism), in the expanded edition of his book on social choice, points out that national-populists like Trump, the Hindu nationalists in India or the Brexiteers behave as if they had a majority among the electorate, but in fact what they do is they take advantage of imperfections of the voting system (like absense of run-off votes or abstention or the Electoral College system in the US) to reach power even against the will of a majority of voters.
7) They are very good at using social pressure, especially in rural areas or small villages, and at using sports players (American footballers or European soccer players or managers) to promote the need for strong men (or women).
8) Simple emotional answers to complex questions are provided for most topics, and their defenders praise this as a positive thing that their too rational rivals should imitate if they want to fight them.
9) There is a constant rhetorical attempt at rescuing the nation-state from its wreckage. They may disagree on how to do it, but they disregard federalist solutions to Rodrik's trilemma that imply rejection of the nation-state as the monopolist of sovereignty.
10) Their selection of the political personnel is purely based on patriotic loyalty or the division of their enemies (like the left), which makes more evident to the rest of the world the low quality of many of their agents. This is probably connected to their rejection of experts.
All this is a danger for democracy, but a more sophisticated danger than a traditional military coup. The paradox is that such sophisticated coup is performed by really unsophisticated people, like Trump or many of the nationalists in Europe (I would include here many Catalan nationalists...). How could this be? Perhaps the answer is in evolutionary biology: self-organization of (really) boundedly rational adaptive agents may produce very sophisticated complex systems. Ask ants or bees.