Department of Defense spokesperson Brig. Gen. Pat Ryder is seen answering questions during a press briefing at the Pentagon in Washington on Tuesday in this captured image. (Yonhap)

The United States is working with allies and partners, namely South Korea and Japan, to deter potential aggression from North Korea, a Pentagon spokesperson said Tuesday, after Pyongyang warned that the Korean Peninsula is on the "brink of a nuclear war."

Department of Defense spokesperson Brig. Gen. Pat Ryder noted the North may conduct a nuclear test to further its escalation.

"So rhetoric aside, again, our focus is on working with our allies and our partners in the region to ensure strategic stability, peace that includes extended deterrence," the Air Force general told a press briefing.

North Korea on Monday accused South Korea and the US of pushing tensions to the "brink of a nuclear war" while arguing that a nuclear war on the Korean Peninsula would "rapidly expand into a world war" that would cause the "most catastrophic and irreversible consequences."

The Pentagon spokesperson underscored the possibility of an additional nuclear test by North Korea.

"And so when it comes to things like nuclear testing we have known for a while as you have heard us say that North Korea at some point will conduct a nuclear test," said Ryder.

"I don't have anything to announce nor would I in terms of when that might be," he added.

Ryder highlighted the importance of US alliances in dealing with threats posed by North Korea.

"Our focus is going to be on continuing to work with our allies to include the Republic of Korea and Japan to deter potential aggression and destabilizing acts," he said, referring to South Korea by its official name.

To this end, the US regularly conducts joint military exercises with South Korea and Japan, Ryder noted, adding, "because our alliances and our partnerships are critical strategic advantage and capability."

Ryder also underscored the importance of trilateral cooperation between South Korea, Japan and the US

"We very much value the relationship that we have with Japan and with the Republic of Korea, and certainly continue to work very closely with those allies to find opportunities for our nations to work together," he said when asked about possible inclusion of Japan in the Washington Declaration, under which Seoul and Washington agreed to establish a Nuclear Consultative Group to discuss how the US should use its nuclear capabilities to deter, or to counter if necessary, nuclear aggression from North Korea.

The Pentagon spokesperson declined to comment on whether Seoul and Washington may expand the Washington Declaration to include Japan.

"But one thing I am positive about is that we will continue to work very closely together, both in the region and elsewhere, to ensure that we can preserve a free and open Indo-Pacific and that we can work together to ensure peace and stability around the world," he said. (Yonhap)