I know it's not what you asked. It is, however, what the conversation was about. As for why offensive and defensive weapons are tied together, I'll have to explain Mutually Assured Destruction to you.
Let's say you and I are holding guns, pointed at each other. We don't like or trust each other, but we still aren't inclined to pull the trigger because if we do that, the other will pull his trigger and we both die. So we stand there, guns in hand, but everyone stays alive. However, one day you see me start to put on a kevlar vest. Once the vest is on, I am well-protected from your gun. (let's ignore "shoot the head." for this scenario, your odds of penetrating the vest are very low) What would you do? Let me gain that advantage over you, or pull the trigger before I get the vest on?
That's what we have going here. Nuclear arsenals that are guaranteed to destroy each other. He who pushes the proverbial button to destroy the other will himself be destroyed, and the human race may fall as a result. Right now, defensive interceptors just aren't up to the task of stopping ICBMs. They're just too freaking fast, the intercept success rate is abysmally low, and that's not even counting the effects of decoys and MIRVs. If some defensive system did come up that truly threatened the capabilities of ICBMs, do you think the Russians would:
A) Allow us to finish building the defensive shield and gain a potentially decisive advantage over them
B) Blow us all to hell before being forced to their knees before us
Developing systems capable of stopping these strategic weapons actually makes us less safe.
Developing systems to protect us from smaller-scale weapons like Iran or North Korea might come up with is not in violation of the treaty, as long as it doesn't seriously threaten the existing strategic stockpiles.
First of all I would like to commend you for a very well written post. You are a gifted writer and thoughtful opponent. You are also like a cat.
Cats see the world in black and white. They do not perceive the rich and textured hues and bright colors of reality. But their inability to perceive this element of reality does not mean that bright colors and rich hues don't exist.
I understand Cold War Era MAD Theory. But thanks for the refresher course. MAD doesn't work against Iran, but I'll get to that in a moment.
Russia isn't going to preemptively attack the US under any set of circumstances. Similarly, the US will not launch a first strike against Russia. That isn't the issue.
Missile defenses cannot be tied to any treaty or limited in any way. The reason is I say that is we have now moved in to what some people call the Third Nuclear Age. There is going to be an explosion of nuclear know how to many states and nonstate groups in the world.
America tried to prevent nuclear proliferation, but the genie is out of the bottle. North Korea and Iran have shown the nations of the world how to use the auspices of the Nuclear Non-Proliferation Treaty to become nuclear weapons states.
In the next twenty five years or so there will be an expansion in the number of nuclear weapons states. MAD breaks down as the number of nuclear weapons states expands. During the First Nuclear Age only America, Russia, the UK and France possessed nuclear weapons. MAD Doctrine worked well because the men with their fingers on the triggers knew what total destruction meant. They had seen it during WWII.
During the Second Nuclear Age China and India developed the ability to master the nuclear fuel cycle. MAD Doctrine still worked because these states were under the control of sober minded people not on a mission from gawd.
We are now in the Third Nuclear Age. North Korea has plutonium weapons and is working on uranium based bombs. They already sold the technology to Syria at the probable behest of Iran. Israel destroyed the Syrian project.
Iran is going to become a nuclear weapons state, and there is nothing effective that can be done to stop in at this late date other than a nuclear first strike, and that's not going to happen, nor should it.
Venezuela, Myanmar and other states will ultimately acquire nuclear weapons. It's inevitable.
America developed nuclear weapons. But Russia was afraid of America. So Russia developed nuclear weapons using some technology passed to them by one or more American scientists who had worked on the Manhatten Project. Then the UK and France got the bomb so they could be in the club.
Russia helped China develop civilian nuclear technology. But the Chinese were afraid of the Russians, so the Chinese used civilian Russian tech to develop their own nuclear program. They got the bomb in 1964.
China and India fought a border war in the Himalayas in 1962. So the Indians were afraid of the Chinese. They started their own nuclear program and exploded a bomb in 1974.
American intelligence believes that the Chinese passed info in 1984 to the Pakistanis on the engineering and physics required to develop nuclear weapons. In the nineties Pakistan became a nuclear weapons state and now has at least one hundred bombs.
Russia also helped North Korea with a civilian nuclear reactor, and Pakistan has admitted to having sold nuclear weapons technology to the North Koreans in exchange for ballistic missile technology. There is no way to stop the proliferation of nuclear weapons technology.
MAD won't work against Iran because the logic of the doctrine is superceded by the messianism of the Twelver Sect of Shiism as practiced among some of the ruling factions in Iran. The Return of The Mahdi requires a cataclysm. Even if MAD Doctrine could work with Iran it is impractical for America. America is no longer willing to fight a serie of proxy wars against a fellow nuclear state. America's problems are at home.
The better and smarter and cheaper course of action is for America to simply withdraw from political and military relations with countries in the eastern hemisphere. If America does that neither China nor North Korea will be a threat. The Chinese and North Koreans will be preoccupied with the nuclear weapons programs that arise in South Korea, Japan, Taiwan and Vietnam.
Iran would complete its nuclear program, but would face the danger of Saudi, Egyptian, and Turkish nuclear weapons programs that arise in response.
America doesn't need to provide missile defenses for Europe or any one but itself. But America must have absolute and complete freedom to develop a multi layered system of missile defenses without any constraint by the Russians. And the Russians will constrain America. A future president may be deterred in doing what is necessary to complete the defense the country needs against other nations, and nonstate groups.
Finally, I apologize for the rambling nature of this post.