SEOUL - South Korea shrugged off North Korea's firing of short-range missiles saying they were part of routine military exercises and warning that more launches are to be expected.

Whether the communist country will fire a long-range missile toward Hawaii remained unclear, though US defence officials said such a launch did not appear imminent.

The North fired four short-range missiles on Thursday, just ahead of the US Independence Day that falls this weekend, a move the US and Japan called "provocative".

The launches have highlighted concerns over North Korea's broader missile intentions, especially after the country warned ships to stay away from waters off its eastern coast until July 10.

While Americans were celebrating Independence Day in 2006, North Korea also fired a barrage of missiles, including a long-range Taepodong-2 that broke apart and fell into the ocean.

Meanwhile, two independent scientists say Mr Kim Jong Il's government may be using an old Soviet ballistic missile to boost a rocket capable of reaching the US.

In a June 29 assessment published in the Bulletin of Atomic Scientists, Massachusetts Institute of Technology professor Ted Postol and Union of Concerned Scientists' David Wright used data and imagery from North Korea's April 4 launch and calculated that the second stage of the North Korean rocket had similar features of an SS-N 6 - a Soviet submarine-launched ballistic missile first deployed in 1968. AP

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