Take Iraq and take North Korea. North Korea is the bigger threat to the US and to its neighbors. Iraq, after a decade of sanctions, was powerless. Who did the US attack? Iraq. Why didn't the US attack North Korea. Because they might have sent a nuke somewhere. We never started wars with the Soviet Union or China. Why? They had WMDs.
If you are a rational non-nuke country who is being targetted by the US, say Iran, what is your only way to ensure your survival? What is your only way to protect yourself from a hyper-aggressive US? Develop WMDs. This is part of the reason that Iran is attempting to get WMDs right now and why North Korea isn't backing down.
The lesson you learn from US foreign policy is that if you are weak you will be mercilessly attacked by the US (see long list of weak countries meddled with or straight up attacked by the US) even if it is wrong. If you have nukes, you run less risk of being attacked. Hence, US foreign policy is promoting the spread of WMDs.
If you are a rational non-nuke country who is being targetted by the US, say Iran, what is your only way to ensure your survival? What is your only way to protect yourself from a hyper-aggressive US? Develop WMDs. This is part of the reason that Iran is attempting to get WMDs right now and why North Korea isn't backing down.
The lesson you learn from US foreign policy is that if you are weak you will be mercilessly attacked by the US (see long list of weak countries meddled with or straight up attacked by the US) even if it is wrong. If you have nukes, you run less risk of being attacked. Hence, US foreign policy is promoting the spread of WMDs.