SEOUL, South Korea — North Korea announced Friday that it planned to launch a satellite into orbit next month, threatening to scuttle a new agreement with the United States that had briefly raised hopes of easing diplomatic and military tensions surrounding the North’s nuclear weapons program.

The United States and other countries swiftly and strongly condemned the step, saying that the launching would violate United Nations Security Council resolutions demanding that North Korea stop launching rockets that use long-range intercontinental ballistic missile technology, like the one that would carry the satellite to space. The United States and the Security Council have condemned such satellite launchings in the past as a cover for developing the missiles, which could eventually be used to deliver nuclear weapons.

The announcement came only 17 days after North Korea agreed with the United States that it would suspend uranium enrichment, allow United Nations inspectors back into the country and place a moratorium on nuclear and long-range missile tests in return for 240,000 tons of food aid over the next year. In Washington, the State Department said that agreement explicitly forbade missile tests or satellite launchings, among other military actions.

The deal had been widely expected to revive broader multilateral talks aimed at dismantling the North’s nuclear weapons program, but the United States on Friday said it was suspending discussions on delivering the food aid and raised doubts about the sincerity of North Korea’s commitments under the agreement.