The Democratic People's Republic of Korea (DPRK) accused the United States on Tuesday of "inciting military tension" by holding joint exercises with South Korea, and said Pyongyang would take measures to defend itself.

Ju Yong Chol, a DPRK diplomat in Geneva, told the UN-sponsored Conference on Disarmament that Pyongyang would have to "reconsider the major steps we have taken so far."

The U.S. and South Korea kicked off their joint military drills on Monday despite Pyongyang's warnings. The DPRK says the joint military exercises are a "flagrant violation" of efforts to reach peace on the Korean Peninsula. 

"Although U.S. and South Korean authorities are playing every trick to justify this military exercise, they can neither conceal nor whitewash its aggressive nature in any manner," Ju told the forum.

"What is more serious is that the United States is inciting military tension hostile to the DPRK by deploying a large amount of latest offensive military hardware in South Korea in disregard of its commitment to suspend joint military exercises made at summit level," he added.

Pyongyang remains committed to resolving issues through dialogue, but this compelled the DPRK to "develop, test and deploy the powerful physical means essential for our national defense", Ju said.

He did not mention the DPRK's latest firing of two unidentified projectiles into the sea off its east coast early Tuesday, the fourth such launch in less than two weeks, Yonhap news agency reported.

U.S. disarmament ambassador Robert Wood took the floor to reject the allegation, saying the U.S. looks forward to returning to discussions with the DPRK in order to carry out the vision agreed by DPRK leader Kim Jong Un and U.S. President Donald Trump at their first summit meeting last year in Singapore.

U.S. Defense Secretary Mark Esper responded on Tuesday and said the U.S. is keeping the door open for diplomacy and will not overreact to the latest missile launch.

Trump's national security adviser John Bolton said on the same day that Trump has an understanding with Kim that Pyongyang will not launch longer range, intercontinental-range ballistic missiles, and the U.S. is watching DPRK missile tests very carefully.

"It looks like it's a testing series that they want to get this missile fully operational," Bolton said. 

(With inputs from agencies)