Naseem Vaziri is an agent for the Iranian government.
He was ordered by the Iranian government to determine who the name of the U.S spy was in Iran, by working with Marcel Janvier to get a flashdrive from a U.S agent named Kevin Atley in order to figure who the name of the spy was.
After Marcel Janvier was supposedly killed by Agent G. Callen, he was forced to use him to figure out who the spy was in Iran.
He first meets Agent Callen after being released from jail and tries to convince him to give him the name of the agent, while also having his men spy on him, but he refuses and defeats his two bodyguards and walks away.
He and his bodyguards then meet with him on a beach after he goes for a swim in the beach, to get him to tell him who the agent is, but like before he refuses again.
Some time later it is revealed that he is working with another man, an adversary of Hetty's named Hosein Khadem, as confirmed when Hetty and Callen caught him and Khadem as well as their men spying on them. After Callen figures out that they are using Hetty as leverage to get Callen to talk, he is then confronted by Callen who demands he take his men of Hetty but he refuses, so Callen tells him the name , which is actually a fake.
Sometime later after figuring out where Atley's file is, he has several of his men retrieve it from a fleeing Agent Marty Deeks, and Kensi Blye , located in a brief case unaware that Deeks switched the flash drive in the brief case.
Later after he suspects that Callen lied, He and his men are able to capture Callen and demands that Callen tell him who the spy is or he would have Hetty killed. Despite Callen's initial reluctance Callen tells him that there was no spy and it was an elaborate ruse against the Iranian government to get a notorious general out of power and that Marcel Janvier is alive and Callen proposes a trade between him for Marcel Janvier, and he eventually accepts and takes Khadem and his men off Hetty.
After a successful trade he has Marcel Janvier brought back to Iran for trial, as he was a wanted fugitive in Iran, as well as retrieving the flash drive he was unaware that was faked.
Later in another episode, it is revealed that he was holding Marcel hostage by his men and that he had one of Marcel's hands cutoff.
Later in the episode he becomes into an allegiance between Isaak Sidorov and Marcel Janvier unaware that this is part of an elaborate ploy of NCIS to capture Sidorov and get him to confess to where he placed his bombs., but this ploy was secretly tipped off by Marcel Janvier to Isaak Sidorov, leading to Marty Deeks's and Sam Hanna's capture by Sidorov.
He then arranges a deal with Sidorov, and a secretly undercover Quinn, relating to Sidorov's stolen nukes unaware that NCIS was watching them.
Later he is lured into a trap by Janvier, by using someone to fake being his daughter. Janvier then kills the girl and cut's off both of his hands in order to get payback for him cutting off his hand.Janvier lets him live to cause him to suffer and show NCIS. He then witnesses Agents Sam and Callen enter into his room and tells them about what Janvier did to him.