WASHINGTON (AFP) - The US military beefed up its Hawaii defences Friday over fears Pyongyang may launch a missile at the Pacific island chain, as it tracked a North Korean ship possibly carrying banned cargo. The vessel, which has been monitored for days, is the first to be tracked under UN sanctions imposed last week after North Koreas underground nuclear test on May 25. US Defence Secretary Robert Gates said Thursday there were concerns that North Korea might launch a missile... in the direction of Hawaii. He said he had approved the deployment of THAAD missile defence weapons to Hawaii and a radar system nearby to provide support in case of a North Korean launch. Ground-based defences in Alaska were also ready, Gates added. I would just say I think we are in a good position should it become necessary to protect American territory, he said. The Theatre High Altitude Area Defence (THAAD) weapons, coupled with the radar system, are designed to shoot down ballistic missiles. US and South Korean officials have said North Korea might be readying another ballistic missile test after three launches in 1998, 2006 and this year. Pyongyang said its latest April 5 launch put a satellite into orbit. The United States and its allies labelled it a disguised test of a Taepodong-2 missile theoretically capable of reaching Alaska. Japans Yomiuri Shimbun newspaper this week quoted Japanese defence ministry sources as saying any new test of North Koreas two or three stage Taepodong-2 missile would probably be fired toward Hawaii even if it could not hit the island chain. It quoted the ministry as saying the Taepodong-2 has a range of 4,000-6,500 kilometres, but that Hawaii is more than 7,000 kilometres from the Korean peninsula. The ministrys analysis said it was most likely the Norths next missile test directed toward Hawaii could take place between July 4 and 8, the daily said. Tensions on the Korean peninsula have been running high since Pyongyang carried out its second nuclear test last month. A US defence official confirmed that the military has been monitoring a North Korean ship, the Kang Nam, that might be carrying nuclear or missile-related cargo in violation of new UN sanctions. There is a particular ship that we are closely monitoring, the defence official, who spoke on condition of anonymity, told AFP. The US military has long kept a close watch on ships heading in and out of North Korea, but the new UN resolution means we have newfound authorities and responsibilities, the official said. The UN resolution calls for inspections of ships but rules out the use of military force to back up the searches. Admiral Mike Mullen, the top US military officer said the United States would vigorously enforce Security Council resolution 1874. If the ship refuses the search, then the vessel would be directed to a nearby port, Mullen told a news conference with Gates. Mullen would not confirm whether the military was tracking a particular North Korean vessel. The United Nations resolution calls on member states to inspect ships if there are reasonable grounds that a vessel may be carrying illicit cargo. Analysts say however that North Korea could get around the shipping measures by transporting banned cargo by air and exploiting provisions that prohibit the use of military force. However, experts say the financial sanctions in the UN resolution could prove more effective against the isolated Stalinist state.