The UN has slapped a global port ban on four vessels found violating sanctions against North Korea. <br/><br/>The designation doesn't mean an assets freeze or travel ban. But it's a port ban, said Hugh Griffiths, coordinator of a UN Security Council panel on North Korea sanctions. <br/><br/>The four ships were found carrying coal, seafood and iron ore, exports banned by a UN resolution brought by the United States in August. <br/><br/>He said, it's a pretty swift and decisive action by the committee. The ban came into effect on October 5.