In May this year, the Russian president urged military commanders to hurry the launch of missile attack warning satellites. The reason he reportedly gave them was: If Clinton wins the US elections in November, we will have a world war next year, and Russia should be ready to defend itself. Regardless of how realistic or unrealistic this is, it is the Russian perception of the likely next US president.
Looking at it from the opposite angle:
(Quoted from her own campaign site.)
"Stand up to Vladimir Putin. Hillary has gone toe-to-toe with Putin before, and she’ll do it again. She’ll stand shoulder to shoulder with our European allies and push back on and deter Russian aggression in Europe and beyond, and increase the costs to Putin for his actions."
Now, there is a problem with this... and that is that US allies don't face any Russian aggression in Europe. Ukraine does, sure, but that is an ally of the United States only because after the aggression, the United States decided to be one.
Let that sink in for a moment. "We will stand with our allies, and we choose our allies such that we get to stand against Russia." If you were a Russian, how would that sound to you?
How would it sound to Americans if they heard, say, Putin say "We will stand by our allies", and then choose to ally themselves with, say, Mexico, holding common military exercise with the Mexicans on their soil? Wouldn't you assume that this is an act of only thinly-veiled aggression against your nation? And wouldn't you prepare to defend your interests in Mexico?
Then there is this recent piece...
http://www.reuters.com/article/us-mideast-crisis-usa-aircraft-idUSKCN10U1ON
"A U.S.-led coalition sent aircraft into northeastern Syria on Thursday in a "very unusual" move to protect American special operation ground forces from attacks by Syrian government jets, a Pentagon official said on Friday."
There have been recent clashes between pro-government forces in Syria and Kurdish forces, and the Syrian government sent air support to their people. If the "coalition", that is, the US in Syria, go actually as far as shooting down Syrian warplanes over Syrian soil, then there's a certain country that will of course feel that it has to "stand shoulder to shoulder with their allies and push back on and deter aggression in Syria and beyond".
You can easily see where this kind of talk leads us all.
According to some anthropologist models, major war (in contrast to minor clashes between single societies) in a given collection of societies happens about every four generations, plus or minus one, because after four generations, people (and most importantly, those people who are leaders) forget just how terrible such a war really is.
It certainly looks like our peaceful time is almost up once again.