UNITED NATIONS — The United Nations Security Council on Saturday unanimously adopted a resolution to impose the most punishing sanctions yet against North Korea over its repeated defiance of a ban on testing missiles and nuclear bombs.

The resolution, intended to press North Korea to renounce its nuclear militarization, could reduce the isolated country’s already meager annual export revenue by $1 billion, or about a third of its current total.

Ambassador Nikki R. Haley of the United States, which introduced the resolution, said its adoption by all 15 Council members signified what she called “a strong, united step toward holding North Korea accountable for its behavior.”

Ms. Haley described the new penalties, which the United States painstakingly negotiated with China, North Korea’s most important trading partner, as “the most stringent set of sanctions on any country in a generation.” She also said they would give North Korea’s leaders “a taste of the deprivation they have chosen to inflict on the North Korean people.”