As the city of Hiroshima, Japan, prepared to mark the 72nd anniversary of the United States’ deadly atomic bombing, the United Nations Security Council voted unanimously Saturday to impose harsh sanctions on North Korea, in the hopes that they will deter the country from using its own nuclear weapons.

The sanctions will cut about a third of North Korea’s export revenue, amounting to about $1 billion in exports per year. Countries will be barred from buying North Korean products including coal, iron, and seafood, and from beginning new business ventures with North Korean businesses or individuals.

The new policy was imposed after Kim Jong-un’s military tested two intercontinental ballistic missiles (ICBMs) in July, demonstrating the weapons’ potential to reach the continental U.S.—possibly getting as far as Chicago.

U.S. ambassador to the United Nations Nikki Haley told the press before the vote, “All this ICBM and nuclear irresponsibility has to stop.” Her warning and the decision to impose the sanctions followed weeks of pressure from the U.S. to China, North Korea’s largest trading partner, to help punish Kim Jong-un’s regime for its missile tests. But before voting for the sanctions, the Chinese ambassador to the U.N., Liu Jieyi, said last week that the U.S. must also attempt peaceful negotiations with North Korea.

“If [the U.S. and North Korea] refuse to move toward what is required by the Security Council resolutions—de-escalation of tension, negotiations to achieve denuclearization and peace and stability and also resume dialogue—then no matter how capable China is, China’s efforts will not yield practical results because it depends on the two principal parties,” said Liu.