GENEVA — A North Korean diplomat said on Tuesday that the United States and South Korea were “inciting military tension” by proceeding with joint military exercises this week, saying they would jeopardize the diplomatic efforts to reach a deal on the North’s nuclear weapons.

The statement from the diplomat, Ju Yong-chol, at the United Nations-backed Conference on Disarmament in Geneva came hours after North Korea launched two short-range ballistic missiles, the latest in a series of tests it has carried out since late July.

Mr. Ju said the deployment of F-35A stealth fighters and high-altitude reconnaissance drones for the military exercises, along with a port call by the American nuclear submarine Oklahoma City, were “hostile acts.” He said they showed that Washington and Seoul still regarded North Korea as an enemy, despite the commitment made last year by President Trump and Kim Jong-un, the North’s leader, to forge a new relationship between their countries.

As a result, “we are also compelled to develop, test and deploy the powerful physical means essential for our national defense,” Mr. Ju told the conference, a multilateral forum for negotiating arms control and nonproliferation agreements.