U.S. national security adviser John Bolton said Saturday that recent short-range missile tests by North Korea that President Donald Trump had dismissed as "very standard" were a violation of U.N. Security Council Resolutions.

North Korea's test of short-range ballistic missiles on May 4 and 9 ended a pause in launches that began in late 2017. 

“U.N. Security Council resolutions prohibit North Korea from firing any ballistic missiles,” Bolton told reporters in Tokyo ahead of the president's four-day visit to Japan. “In terms of violating U.N. Security Council resolutions, there is no doubt about that.”

The missile tests appeared to be an attempt by North Korea to pressure Washington over stalled talks on potential de-nuclearization of the Korean peninsula.