halacha - Is it halachically ok to buy and sell cigarettes?

I live in a country where cigarettes are very cheap. I am going to travel somewhere where I can sell cigarettes for much more than it cost me. If I take them, I will make a huge profit.

However I am concerned that it may be halachically incorrect to sell these cigarettes to other Jews because it may be a transgression of lifnei Eiver Lo Titen Michshol - One must not place a stumbling block before a 'blind' person.

To establish if this is in fact prohibited we must first make sure that smoking in the first place is prohibited. I always understood that it was completely forbidden due to the prohibition of committing suicide (correct me if I am wrong).

However, one can argue (this is what many friends of mine tried to argue) that they are going to smoke the cigarettes anyway since they are addicted. So there should be nothing wrong with being the one who provides them.

I would like to know which side is correct (please bring sources to any answers) Thanks

Edit: as Daniel mentioned in the comments, I think it is actually illegal to do such a thing. I presume that this also makes it halachically incorrect?