WASHINGTON (Yonhap) -- A senior Pentagon official on Thursday emphasized the need for "optimal readiness" against additional provocations from North Korea.

"North Korea's April 12 missile test will not be its last," Kathleen H. Hicks, the nominee to become principal deputy under secretary of defense for policy, told the Senate Armed Services Committee at a confirmation hearing.

She has been serving as deputy under secretary of defense for strategy, plans and forces since 2009.

"The United States must continue to monitor carefully North Korea's weapons of mass destruction and missile development programs and related proliferation activities," she added.

Pyongyang claims its Taepodong-2 is designed for a space program, but it could reach the U.S. if developed as an intercontinental ballistic missile, she said.

Hicks vowed efforts to "ensure optimal readiness against North Korea's unpredictable and reckless behavior."

Concerns are growing that the North may carry out a third underground nuclear test.

It conducted nuclear experiments in 2006 and 2009, both coming on the heels of long-range missile launches.