Is America to blame for North Korea's nuclear weapons program?

Up until January 2003 North Korea were part of the Nuclear Non-Proliferation Treaty (NPT). The objective of said Treaty is to prevent the spread of nuclear weapons and weapons technology, promote cooperation in the peaceful uses of nuclear energy and to further the goal of achieving nuclear disarmament. On the 10th of January the North Koreans gave notice of a withdrawal from the Treaty alleging that the U.S. had started an illegal uranium enrichment program. The withdrawal became effective on the 10th of April, but did they really pull out because of an illegal enrichment program?

In September 2002 George Bush had begun formally making his case to the United Nations for an invasion of Iraq; stating Iraq was "a grave and gathering danger". In his state of the union address the following January he refered to North Korea, Iran and Iraq collectively as the 'Axis of Evil'. By February an invasion was almost certain and by March troops were on the ground in Iraq. Kim Jong Il watched as George Bush followed through on his administration's preemptive strike policy, I believe this to be the event that significantly increased North Korea's drive to build nuclear weapons. It would seem Kim Jong Il felt Saddam was ousted because he didn't have nuclear capabilities, the world takes you seriously when you have a nuclear bomb. 

Three weeks after the invasion of Iraq, North Korea officially withdrew from the NPT and three years later they announced they had successfully tested a nuclear device. It would appear that North Korea invested in nuclear weapons technology as a defence strategy and not to attack the rest of the world like the US government would like everyone to believe. 

While I'm not condoning it, building nuclear weapons to protect yourself from a global bully could be considered a perfectly rational response. If North Korea ever do use a nuclear warhead, aggressive American foreign policy will be largely to blame. Not that they'll ever admit that.