It has been three years since North Korea last tested submarine-delivered missiles, which pose a particularly serious challenge because they are harder to detect and extend the range of the North’s arsenal.
"We'll be ensuring that whatever cooperation that's existing between North and South Korea today on Olympic teams does not cloud the reality of a regime that must continue to be isolated by the world community," Pence told reporters.
The Hwasong-15 missile, described as North Korea's "most powerful", was launched in darkness early on Wednesday. It landed in Japanese waters but flew higher than any other missile the North had previously tested.
In a government statement released through state media, North Korea said the Hwasong-15, the "greatest ICBM,'' could be armed with a "super-large heavy nuclear warhead'' and striking the "whole mainland'' of the United States.