The sec I have nukes, I use nukes:)

Well sometimes it is just epic seeing it land on a city, sometimes you need to use it against enemies etc.

And btw I was exaggerating a bit.

Make threat defence systems and SAM launchers (Threat defence systems are preferable).

Yeah thats how it works with all the Anti air... I suggest you build lots of them and place them around your country. Every type of air defence sadly has that. What i do is i mobilize anti air and Sam launchers. Then i upgrade them enough to be able to transport them via airlift. I then stack 5 anti air and 5 Sam launchers. Its a super strong combo and ive been in a 5v5 nation war without getting any enemy airplanes in my airspace :). try it out!

Air superiority can deal with your strike fighter problem, especially GOOD air superiority(like the F-22)

I got nuked by four ICMB!!!

I had a Threat defence systems around my city to protect them.

The city is destroyed and also my Threat defence systems?!

What I am doing wrong?

To kill incoming missiles, you need to kill it. Reduce its HP to 0. That being said, you need to have enough missile killing capabilities to kill incoming missiles in 1 hit. You can see how much HP a missile has in the tech tree. 1 TDS is rarely enough, better take 4

So I wonder, every unit loses combat strength when damaged, but missiles don't?

So whats the formula? a ICMB has 40x HPs, a Balistic one has 10x HPs....

In one game I shot many balistic ones, but I had 6x TDS units to shoot it down. How many do we need of a ICMB?

I want to say I personally agree with your philosphy. I only used nukes when I first started playing in my very 1st game. I wanted to see what it was like. I am not sure how many games I have played now I would guess 30 or so and havent even resources them once since then. That being said keep in mind how you build and play is not how everyone else does and if they are available someone will use them. I am actually currently in a game where I am in a coalition with someone that I have played with in the past and he is using them. Now personally I will say this. If you use them I say late game (literally if server is like 100+ days) and you are finishing up. I say this for several reasons. #1 it kills morale. the large loss of civilian life lowers morale which lowers your ability to make resources. #2 the cost a decent amount of resources to make them.

Now in the case I was referring to with my coalition mate he used them very early. (I think like day 10 or so) now I dont use gold I assume he did that is part of the game so whatever but before he used them he mentioned in a message he would. I told him dont my ships were already taking care of the stack he was referring to. my ships were in place I go to bed and wake up and he nuked a stack of 10. that my ships could have cleared out. Now he has lower morale and wasted a nuke for nothing my point is using them carelessly like that is a huge waste. If you want to build them fine it is part of the game.

#1 If they were available and no one used them the developers would be wasting there time with that in the game.

#2 There is a penalty (morale drop from civilian casualty) if you want to deal with that go ahead. Also this is why I do not use them. From a person not using gold this is a lot to overcome. You depend on that resource prodiction

#3 There are defenses for it but I will say if someone is making a lot of them. and just firing a bunch of nukes all over randomly it is very difficult to defend that. I will say that doesnt happen very often. I think because it would take a lot of gold. and although obviously people use gold a good amount (which is not a bad thing by the way) I love this game and it is fun. I do support by buying sc but I like the strategy aspect and choose to play without using gold. But the gold users help the developers make money. Just wanted to add that. Back to subject I dont think it is smart to use that much gold to be able to do that. I have seen it before where you get the nuke message everyday because of 1 or maybe 2 players but it is rare.

Never used nukes, but had one enemie who used golden nukes on us.

If you don't use them smart, they are only an annoyance.

Honestly I don't like missile in general that much, probably to much of a roleplayer in heart. That is why, I don't like unnecessary civilian casualities.