Get help from who?the entire middle east hates iran for some reason,and unlike vietnam where supplies could be directly recieved from adjacent china,ussr through china,here is not the case.
iran is on its own,now us in afganisthan is going to stay busy,but they are withdrawing from iraq in a rapid pace,so after the withdrawal is complete,us could just feel free to attack iran.
now lot of members are saying 11 million paramilitary forces and huge standing army will crush us land forces and all that but they have to understand modern wars are won by concentrating firepower rather than manpower.
now they say that iran if attacked will attack puny american land force in afganisthan and sweep it away.the problem is lack of air cover,in a modern war no offensive action is possible without air supremacy as egypt learned vs israel.secondly when attacking u have to operate outside ur country that is ur natural logistical base.its no good having millions of personnel if u can't keep them supplied,tanks need ammunition,vehicles need spares,artillery shells and the army ammunition.to keep ur army in a fighting condition u must have an industrial base to continously build these and supply them.these are not like days when people fought with swords.
first of all, us army intelligence is second to none,any mass concentration of land forces will be picked up by satellites and jstor intelligence planes.and they will come under murderous aerial strafing and bombing and ur supply lines interdicted and industrial base under assault.so i am afraid iran will have to eventually resort to guerilla fighting afghan style.luckily for them they have a large pool of motivated manpower to do that,however they don't have safe haven from american forces like taliban had in nwfp to regroup after setbacks.so they just have to hold tight and wait for u.s public opinion to shift.
The unfortunate or fortunate[depending on ur pov] fact is no nation at present can really win a conventional war against usa.it is a fact we must live with.