U.S. and South Korean officials said the test, from an area north of the North Korean capital, appeared to have failed, in what would be the North‘s fourth straight unsuccessful missile test since March.

The test came as the USS Carl Vinson aircraft carrier group arrived in waters near the Korean peninsula, where it began exercises with the South Korean navy on Saturday, just minutes after the failed launch, a South Korean navy official said.

“The threat of a nuclear attack on Seoul, or Tokyo, is real, and it’s only a matter of time before North Korea develops the capability to strike the U.S. mainland,” Tillerson said.

“Failing to act now on the most pressing security issue in the world may bring catastrophic consequences.”

U.S. President Donald Trump said the launch was an affront to China, the North‘s sole main ally.