SEOUL, South Korea - South Korea's president vowed Tuesday to turn five islands along the North Korean border into "military fortresses," heightening tension in an already unstable relationship between the two countries.

President Lee Myung-Bak said the islands would be impervious to attacks similar to the one North Korea launched on Yeonpyeong Island, Nov. 23.

That attack killed two South Korean Marines and two civilians.

CBN News Military Reporter Chuck Holton is in Seoul, South Korea, and says residents are continuing their daily routines, despite their country's battle with the North.

Last month's artillery barrage was only the latest in a series of provocations by North Korea.

But South Korean officials are taking a measured response by conducting military training near the disputed area.

Monday, Secretary of State Hillary Clinton met in Washington with her South Korean and Japanese counterparts to denounce the attacks, as well as North Korea's nuclear program.

She called on China to use its influence over North Korea to reduce tension on the Korean peninsula.

Also Monday, the international criminal court began investigating the Yeonpyeong Island bombing to see if the attack constitutes a war crime.

Meanwhile, North Korea continues to threaten its neighbor to the South -- something residents have grown accustomed to nearly 60 years after the stalemate that brought a stop, but not an end, to the fighting on the Korean peninsula.