US to impose 'toughest ever' sanctions on North Korea, Pence warns

Speaking from Tokyo alongside Japanese Prime Minister Shinzo Abe, Pence didn't detail what the sanctions would be but he said they'd aim to halt Pyongyang's nuclear and ballistic missile program "once and for all."

"Together with Japan, and all our allies, we will continue to intensify our maximum pressure campaign until North Korea takes concrete steps toward complete, verifiable, and irreversible denuclearization," Pence said.

The Vice President arrived in Tokyo Tuesday night and is scheduled to attend the Winter Olympics' Opening Ceremony in South Korea Friday.

Pence told reporters en route to Tokyo that the purpose of his trip was to "make sure that North Korea doesn't use the powerful symbolism and the backdrop of the Winter Olympics to paper over the truth about their regime."

North Korea is sending a large delegation to the Games that includes athletes, cheerleaders, a member of the country's popular girl band Moranbong and even Kim Jong Un's sister.

Their attendance was the result of negotiations during the first high-level, inter-Korean diplomatic meetings in more than two years.

North and South Korean athletes will march under the same flag during the Opening Ceremony and will field a joint women's ice hockey team, signs of unity that have some in the South calling these Games the "Peace Olympics."