The United States said on Thursday that it will continue to take "appropriate action" to influence the Democratic People's Republic of Korea (DPRK), making its leadership take constructive steps toward denuclearization and regional stability.

"We want to see North Korea fundamentally change its approach to its neighbors ... and take affirmative steps toward denuclearization," said U.S. State Department spokesman Philip Crowley.

"Right now, the responsibility is theirs and we would like to see them take responsibility for what they've done, but more importantly take constructive steps along the lines of the commitments that they have made to the international community and to the Six-Party process," said Crowley.

U.S. Secretary of State Hillary Rodham Clinton told reporters on Wednesday in Seoul that the United States will introduce new "country-specific" sanctions against Pyongyang.

The United States and the Republic of Korea have agreed to stage a series of joint naval and air drills starting next week. The first joint exercise involving the U.S. aircraft carrier USS George Washington will take place on July 25 in waters off the east coast of the Korean Peninsula, and the two allies plan to stage more drills down the road in both the Yellow Sea and the East Sea.

"These are exercises that are designed to improve our coordination and training and capabilities with our South Korean allies. They're not meant as a provocation," Crowley stated.