Seth Shakir was a terrorist who planned to knock out the national power grid which would leave the U.S and Canada exposed and potentially vulnerable to a terrorist attack.
He was also wanted for the bombing of a United Nations Headquarters in Baghdad, Iraq on August 19, 2003. He escaped Iraq through Syria.
Eventually, NCIS were successful in tracking him down. They found him just as he was preparing to blow the nodes which would result in power failing in the Virigina area before spreading nationwide.
As he saw Gibbs, Kate and Tony, he shot at them with a machine gun, intending to kill them which forced the three Agents to duck for cover while firing back from the car.
During the battle, he lost his glasses and attempted to finish what he started, forcing a stand-off between himself and the Agents but Gibbs managed to shoot Shakir in his right arm, leaving the terrorist temporarily crippled.
Despite orders from Gibbs to freeze, Shakir refused and devoted the last of his strength, trying to detonate the bomb but was shot by Gibbs, Kate and Tony at the same time which killed him straightaway.
Shakir was a terrorist highly devoted to his cause and more than willing to get the job even if it means he will die in the process.
He also intends to die fighting for the cause as seen when he starts shooting at the NCIS agents who intend to arrest him.
As a terrorist, Shakir was skilled in the use of weaponry and was seen using a AK-47 while attempting to stop Gibbs, Tony and Kate.