US

US, S. Korea, Japan vow cooperation over N. Korea sanctions

  • South Korea's Special Representative for Korean Peninsula Peace and Security Affairs Kim Hong-kyun, center, poses with U.S. State Department's Special Representative for North Korea Policy Joseph Yun and Japanese Director-General Kenji Kanasugi, right, prior to their trilateral meeting to coordinate strategies on North Korea, in Seoul, South Korea, Tuesday, Dec. 13, 2016. (AP Photo/Ahn Young-joon)

    South Korea's Special Representative for Korean Peninsula Peace and Security Affairs Kim Hong-kyun, center, poses with U.S. State Department's Special Representative for North Korea Policy Joseph Yun and Japanese Director-General Kenji Kanasugi, right, prior to their trilateral meeting to coordinate strategies on North Korea, in Seoul, South Korea, Tuesday, Dec. 13, 2016. (AP Photo/Ahn Young-joon)  (The Associated Press)

  • Delegation of South Korea, center, the Unites Stats and Japan, right, attend their trilateral meeting to coordinate strategies on North Korea, in Seoul, South Korea, Tuesday, Dec. 13, 2016. (AP Photo/Ahn Young-joon)

    Delegation of South Korea, center, the Unites Stats and Japan, right, attend their trilateral meeting to coordinate strategies on North Korea, in Seoul, South Korea, Tuesday, Dec. 13, 2016. (AP Photo/Ahn Young-joon)  (The Associated Press)

  • South Korea's Special Representative for Korean Peninsula Peace and Security Affairs Kim Hong-kyun, center, poses for a photo with U.S. State Department's Special Representative for North Korea Policy Joseph Yun and Japanese Director-General Kenji Kanasugi, right, during their trilateral meeting to coordinate strategies on North Korea, in Seoul, South Korea, Tuesday, Dec. 13, 2016. (AP Photo/Ahn Young-joon)

    South Korea's Special Representative for Korean Peninsula Peace and Security Affairs Kim Hong-kyun, center, poses for a photo with U.S. State Department's Special Representative for North Korea Policy Joseph Yun and Japanese Director-General Kenji Kanasugi, right, during their trilateral meeting to coordinate strategies on North Korea, in Seoul, South Korea, Tuesday, Dec. 13, 2016. (AP Photo/Ahn Young-joon)  (The Associated Press)

Top nuclear envoys from South Korea, the United States and Japan have pledged to work toward implementing new sanctions against North Korea, including capping the country's coal exports to choke off cash flowing into its nuclear weapons program.

After a meeting in Seoul on Tuesday, the envoys also said the countries agreed to maintain a round-the-clock information sharing system to monitor how sanctions are working.

Responding to the North's nuclear and missile tests this year, the United Nations Security Council recently voted to tighten North Korea sanctions by placing a cap on the country's coal exports, one of its major foreign currency sources.

South Korea and Japan also announced their own new, unilateral sanctions against the North following the toughening of U.N. measures.