Pentagon spokesman Air Force Brig. Gen. Patrick Ryder speaks during a briefing at the Pentagon in Washington, Nov. 8. AP-Yonhap

The United States is closely watching the suspected delivery of North Korean artillery shells to Russia, a Pentagon spokesman said Tuesday after Pyongyang dismissed U.S. reports that it may be covertly supplying arms to Russia for use in Ukraine.

Defense department spokesman, Brig. Gen. Pat Ryder, however, declined to comment when asked if the shipments have been received by Russia.

"I am not going to have anything new to provide beyond what the NSC (has said), and as you highlight, the information we have is that the DPRK is covertly supplying Russia with a significant number of artillery shells," Ryder said in a daily press briefing, referring to North Korea by its official name, the Democratic People's Republic of Korea.

National Security Council spokesman John Kirby said last week that North Korea is covertly supplying a "significant number of artillery shells" to Russia while trying to obfuscate the real destination of its shipments by funneling them through third countries.

North Korea's military denied the report on Tuesday (Seoul time), accusing the U.S. of spreading "groundless" rumors against Pyongyang in an attempt to tarnish its image.

Ryder said the U.S. "will continue to monitor that situation."

The Pentagon spokesman also reiterated that the U.S. is prepared for any range of contingencies that may be caused by North Korea, including a North Korean attack using an electromagnetic pulse (EMP).

"We prepare for a variety of contingencies in situations," he said when asked about the possibility of a North Korean EMP attack.

"I am not going to get into specifics about any particular tactics, techniques or procedures other than to say that we regularly conduct exercises, training, sharing of information with our ROK allies and other allies in the region on how to work together, how to ensure that we are interoperable and be prepared to respond in defense of our mutual interests, and in this particular case the Republic of Korea," added Ryder. (Yonhap)