There was no treaty. They called a truce. The UN is the arbitrator. They should be acting as we speak. I believe the UN Secretary is Korean...It may present a problem just as Obama presents a problem with his Muslim roots and upbringing.
Unless you think we are South Korea, and North Korea is our ally, she was probably referring to the Mutual Defense Treaty which binds the United States to stand with our South Korean allies. But I'm sure you knew that. "There was no treaty" was probably just a typo, right?