President Donald Trump has ordered the US military to resume nuclear testing.

He has ordered the first nuclear test in 30 years to "continue to maintain peace" with countries such as China and Russia.

"Other countries are testing nuclear weapons. I have ordered us to continue testing," he said.

Trump made the remarks ahead of a meeting with Chinese President Xi Jinping in South Korea.

The president said the United States has the largest nuclear arsenal of any country.

He cited Russia as the second-largest country, with China "a distant third."

The United States has not tested a nuclear weapon since 1992.

Trump strongly condemned Russia's recent nuclear missile test.

Trump has said on social media that "nuclear weapons are devastating," but that he has "no choice" but to modernize America's arsenal while in office.

He said China's nuclear weapons capability would be equal to that of the United States "within five years."

He did not give details on how the nuclear weapons testing would be carried out, but said it would "start soon."