The United Nations has banned four ships from visiting any global port, after they were found violating sanctions imposed on North Korea, the "Petrel 8", "Hao Fan 6", "Tong San 2" and "Jie Shun". The UN Security Council expanded sanctions on North Korea last month in response to Pyongyang's sixth and largest nuclear test yet. The ban was announced following a UN meeting on Oct 9, 2017. The ships were found transporting prohibited goods. The ban, which went into effect on Oct, did not entail asset freezes or travel bans. In August, a UN resolution banned exports of coal, seafood and iron ore from North Korea. Sanctions were expanded last month to include the export of textiles and North Korean guest workers, as well as a cap on oil imports. The tightening of trade restrictions followed Pyongyang's sixth nuclear test and the firing of two missiles over Japan. North Korea's main economic partner China has signed up to the measures, along with Russia. Both have previously vetoed harsher sanctions on the secretive state.