What would the response be if one of the "usual suspects" Iran/north korea sold or gave nuclear weapons to a terrorist organisation who then smuggles them into a few cities and detonate them ?
Would it be treated as if the countries had done the attack themselves ?
First of all Iran doesn’t have the bomb.
There is no simple answer to it. It will depend on the decision makers and nuclear Command and Control (C2) of the state. My opinion is that if a state is involved then terrorist can be viewed as a "
Human Warhead" or what ever terminology you want to use. That would mean that the state has carried out the nuclear strike and does qualify for a nuclear retaliation. If the Non State Actors (NSA) have acted on their own then several things have to be evaluated:
i. In which state the NSA are situated
ii. Does it enjoy the support of the state
iii. If the state where terrorists exist, does not support them then is there any 4th state or party involved.
iv. Do the states where terrorists are situated or from the one they receive support from posses WMDs
v. What is the capability (military, political and economical) of both the states as well as the terrorists (can they carry similar strike again?)
vi. Relationship between the two states
If the NSAs carried out the strike on their own then following actions are forseeable:
i. International pressure on the state where terrorists are situated to smoke them out and take lethal action.
ii. Military strikes (maybe of international forces) on 4th state or party harboring support to terrorists. Surgical or massive conventional strikes can be carried on its nuclear facilities, regime can be overthrown, send it back to Stone Age etc… However, for the state on which WMD strike has been carried out it may become imperative for its decision makers to carry out a nuclear strike since the deterrent thresholds have been breached. If it doesn’t then other suicidal states in future may attempt similar actions again.
If a bomb/bomb making material gets stolen/lost because of neglect and then used in a terror attack what would the consequences be for the country who lost them?
Bombing making material, usually referred to as fissile material, is of NO use to terrorists. In principle two types of fissile materials are used for the making of nuclear weapons. One is Uranium and the other is Plutonium, both have their own inherent natural as well as manned security features.
i. Uranium
Uranium (U) found in nature has an isotopic composition of U238 and is 8th hardest metal in the world. In essence U238 does not qualify as fissile material. It is non-implosive and radiation emission is minimum. Only U235 can make the bomb. U235 is separated from U238 - enriched to 90% (90% makes it weapons grade material - referred to as Highly Enriched Uranium or HEU). This requires large number of centrifuges - in hundreds and thousands. Centrifuges are one of the most sophisticated technologies and not easy to construct.
So, if a terrorist somehow gets U238 (uranium ore) the best he can do is throw this metallic-rockish ore at high profile target and injure him. A head injury might kill the target but hurling uranium ore hardly qualifies as a WMD attack. Uranium can be handled with regular industrial means but terrorists will need to enrich the uranium to U235. The question are Where will they get enrichment facility and centrifuges? and How will they operate it on their own?
It technologically impossible.
The U235 is found in reactors. Terrorists lack capability to extract it from the reactors and further the reactors are kept in highly secured multi-layered facilities. In addition the enriched uranium is quite radioactive and naked exposure to it can and usually does develop cancer in the human body.
Terrorists can acquire an insider help but that too will be worthless attempt. Different scientists and engineers have different responsibilities. How would they get hold of the right person? and how will that right person manage to extract uranium and take it out of the facility and manage to avoid cameras, security personnel and his own colleagues? If multiple people are involved then the word is doomed to get out as intelligence within and surrounding the facilities is very strong.
How would the terrorist be able to attack a nuclear facility? You expect them to come in their pick up trucks, jump off, crash the gate and take whatever they want? While the entire security is on the leave (sarcasm). Its not just the nuclear facilities are secured but surrounding areas as well, in miles and kilometers. Any terrorist attempt to attack will be intercepted even before facility is visible to terrorists.
ii. Plutonium
Plutonium (Pu) is the bi-product of Uranium. It is man made element (meaning not found in nature). Isotopic composition of Pu239 is used for making of nuclear bombs. Smaller quantity of Pu239 can create greater explosion then uranium of same or bit greater size. Production of Pu is very painstaking and lengthy. Uranium fuel rods are put through reprocessing where only fraction of uranium turns into plutonium. Pu is also found in nuclear waste and you have to separate it from all the other elements found in the waste.
In addition to it's production being virtually impossible for terrorists (same as u235) the issue is plutonium is highly toxic and any exposure to it will kill any living being instantly. It cannot be handled with regular industrial means either. Pu is always kept in special enclosed metallic compartments/boxes (made from beryllium I suppose) which reflect its alpha and gama rays back into the pit (if kept in warhead) or back to the fissile material (if in compartments). In compartments scientists and engineers use very thick rubber gloves to handle Pu and even then they can feel the heat emitting from it. A small quantity of Pu (depending on its composition) in a glass can warm up your room. You can try in winters but there will be no more winters for you after that day.
So you see it’s virtually or technologically impossible for a terrorist to gain fissile material and put it to good use. Only a state level assistance can help handle fissile material &/or make a nuclear bomb. That is why both fissile material and bomb only exist with governments till date.
Would the response differ depending on who was attacked ? (Usa, China; Russia, Israel, A Nato country without wmds,, a neutral country)
As I said before it will depend on the decision maker (and note that every decision maker is a rational actor). I am of the view that states making nuclear doctrines, especially ones emphasizing on 2nd strike (they will only attack if enemy carries out nuclear attack on them 1st), and nuclear posture reviews are wasting their times and fooling others. If your country is conventionally weak, you lack strategic depth and your enemy has almost decimated you will you wait for your enemy to carryout 1st Strike? I don’t think so. Even if your country is conventionally strong with greater strategic depth you cannot wait out on your enemy if he puts you in a position where nuclear strike from either side is imminent.