A rocket blasts off from a mobile launcher in this photo North Korea's state media KCNA released on Sunday, a day after the nuclear-armed North fired multiple short-range projectiles into the East Sea. Yonhap

Acting U.S. Defense Secretary Patrick Shanahan said Wednesday that North Korea fired "rockets and missiles" last week, the first time the Pentagon has described the weapons tests.

Shanahan was referring to North Korea's tests on Saturday (local time) of what it has called multiple rocket launchers and tactical guided weapons.

The firings appeared to signal Pyongyang's frustration with Washington over stalemated negotiations on dismantling the North's nuclear weapons program in exchange for sanctions relief.

"I went for a run and then Chairman Dunford called me up and said North Korea was now shooting rockets and missiles," Shanahan told a congressional hearing, referring to U.S. Joint Chiefs of Staff Chairman Gen. Joseph Dunford.

The comment came as Shanahan recalled a series of events that unfolded over the weekend. The North Korean launches occurred Friday evening, Washington time.

While some analysts say the test may have involved a short-range ballistic missile, the U.S. and South Korea have not used that characterization in an apparent effort to keep diplomacy between Washington and Pyongyang alive.

North Korea's use of ballistic missile technology is banned under multiple United Nations Security Council resolutions.

North Korean military fires multiple short-range missiles. Yonhap

In an interview with Fox News on Sunday, U.S. Secretary of State Mike Pompeo said Washington still has "every intention" to negotiate with North Korea and added that the Pentagon is analyzing the tests.

U.S. President Donald Trump also expressed his confidence that North Korean leader Kim Jong-un will honor his commitment to denuclearization.

"I believe that Kim Jong Un fully realizes the great economic potential of North Korea, & will do nothing to interfere or end it," he tweeted Saturday, alluding to the U.S. promise of economic concessions in exchange for denuclearization.

"He also knows that I am with him & does not want to break his promise to me. Deal will happen!" Trump said.

Trump and Kim held a second summit in Vietnam in February to negotiate the details of North Korea's denuclearization and sanctions relief from the U.S.

The meeting ended without an agreement due to differences over the extent of measures each side was willing to take. (Yonhap)