She said Washington had no choice but to put pressure on Pyongyang, and was discussing with its allies how to "further isolate" the regime.
In April 2009, a North Korean rocket launch took place while two American journalists, Laura Ling and Euna Lee, were in North Korean custody after allegedly trying to sneak into the country across the Tumen River dividing the North from China.
They were sentenced to 12 years of hard labor before being released on humanitarian grounds after Clinton flew to Pyongyang to negotiate their release.
Subsequently, three other Americans were arrested and eventually released by North Korea. All three are believed to have been accused of illegally spreading Christianity.
North Korea has several sanctioned churches in Pyongyang but frowns on the distribution of Bibles and other religious materials by foreigners. Interaction between North Koreans and foreigners is strictly regulated.
AP writers Foster Klug and Sam Kim contributed to this report from Seoul, South Korea.