Japan capitulated because of USSR invading korea rather than the nuclear bomb, many historians are proving that

http://foreignpolicy.com/2013/05/30/the-bomb-didnt-beat-japan-stalin-did/

They are not "warning" anyone. They only want to stay in control. The whole world, and especially Japan experienced the bombs. The US did not experience anything other than that they know that they are in possession of a weapon that can annihilate any threats.

If up against overwhelming odds, I would consider it. Consider Japan's circumstances at the time of surrender: Japan's major ally Germany had long surrendered, its cities were getting bombed with almost no way to retaliate, the USSR had just declared war. It's a culmination of factors that brought Japan to the surrender table, not just one. Bombing alone doesn't bring surrender but it can still play its role. Provides incentive: surrender and the bombing stops.

Funny you accuse the United States of wanting to stay in control when for the past decades, the US has been dismantling its stockpile in collaboration with their European allies and the USSR/Russia. Seems more like an attempt to avoid a catastrophic world war than to try to "stay in control".

The US for example still has more than half of its 1990 arsenal. And estimated destruction capability is still about 2/3.

Stockpile in the 60's was way bigger though and there already was a massive reduction in the 70's and 80's.

Soviets and later Russia at some point had an even bigger stockpile but also reduced it massively. But US and Russia combined have an estimated destruction capability of 4.000 megatons> 4.000.000 kt. That ist 200.000 times the Fat Man bomb which destroyed Nagasaki , just more accurate.

Again, this is the reduced stockpile of today. Without the giant multi megaton devices of the 50's and 60's.

I do understand why U.S. used these bomb in a certain way.... what i don't understant its why TWO ? one single one and a warning for more should have been enough for japan to surrender, juste for this, i  call  them monster !

From Wiki:
'A uranium gun-type atomic bomb (Little Boy) was dropped on Hiroshima on August 6, followed by a plutonium implosion-type bomb (Fat Man) on the city of Nagasaki on August 9.'

So USA was testing two different types of nuclear bombs. Thats why it was two bombings. 

Yeah but its why i call them monster :D  the first is somewhat jusified not second one !

Implosion type was tested with Trinity. Cause they did not know if it would work as planned. Gun type didn't need testing, which is why they dropped it without.

Main reason for the nukes was to keep the Soviets out of Japans surrender and following negotiations as well as demonstrating power because the Soviets had the way bigger conventional army.

Why Japan did not react immediately:
Conventional bombings kept on until the 15th of august and actually no one directly realized what had happened in Hiroshima.
There's other stuff as well. The Soviets atteacked Manchukuo, basically a japanese puppet state at august 8th.

There was a discussion in the US on why spending 2 billion dollars for weapons and then not use them.

And so on. Basically there's no single and simple point. But effectively the cold war forecasted it's shadows as soon as WW II had ended, so politics against USSR was an important part.

What sucks though is the US army and scientists using Hiroshima and Nagasaki basically as big labs to study the effects of the bombings like radiation sickness.

How do you know this?

Your reasoning is terribly flawed. Have you considered the possibility that perhaps there were two bombings because the Japanese were still not willing to surrender following the first atom bomb?

Well, maybe you need another 9/11, since you didn't surrender after the first one?