The real issue with folks in Congress and, especially, the media when speaking about nuclear weapons is they mostly don't have clue-one about how they work, what they're actually capable of, etc.
I spent much (not all) of my flying career in the business of being part of our nuclear triad: the air-launched version. I have sat alert with an aircraft "nuked up" to the hilt. When my base had an active alert force, we had five bombers on alert. Each aircraft was armed with 22 weapons (this is no longer classified, for those that are interested). The five aircraft, alone, constituted the fourth largest nuclear power on earth. We were more powerful than nations.
When you deal with these weapons, you learn about them. You learn what they do, how they do it, and what the ramifications of using them are. While it's easy to say a national leader might be "desperate" and willing to use them, you have to remember that it's not one individual that controls these weapons. Well, at least in terms of Russia, the USA, France, Great Britain, Israel...I can't speak for the other nuclear nations. All the briefings I had (again, years ago) said that the other nations were just like us: several people had to agree to employ these weapons.
Small Team Bacsi made a good point and one worth remembering: in October 1962, the world came close. Military leaders in Washington were considering the tactical use of small nuclear weapons in Cuba, if necessary. The Soviets were considering using them to break a military blockade. In the end, it almost happened. Read about Vasili Arkhipov; considered by many to have saved the earth.
I don't think the Russian people/government would consider the use of nuclear weapons unless M1-Abrams were rolling up on Red Square...and even then.
Of course, my opinion and $1.08 will get you an XL Polar Pop at Circle K. So judge accordingly.
Steve
PS. If you want to get just a small "idea" of what nukes do...google "nuke map" and you'll find a webpage where you can "nuke" things to your hearts content. It's, actuall,y pretty accurate.