South Korea Raises Port Security As Tensions Rise with the North

South Korean officials warned oil tankers, cargo vessels and commercial ships traveling near the maritime border to take extra security precautions after fears of war on the Korean Peninsula escalated Wednesday. Tensions across the region mounted after North Korea bombared a South Korean island with artillery, killing four people and injuring 18 others on Tuesday. However, there are no signs the incident has showed shipping traffic along the coastline of Asia's fourth largest economy.

UN Secretary General Ban Ki-moon called it one of the "gravest incidents" since the end of the Korean War. The North says they attacked Yeonpyeong Island as a response to the South holding a military drill off their shared coast in the Yellow Sea.

Further leading to tensions in the region, a nuclear-powered U.S. aircraft group that carries 75 warplanes and a crew of 6,000 was heading to Korean waters as part of the joint exercises with South Korea. The USS George Washington left a naval base south of Tokyo and would join in the exercises with South Korea in the Yellow Sea. U.S. military officials said the move was planned well ahead of the North Korean attack, but added the move "demonstrates our commitment to stability through deterrence."

China is also likely to be enraged with the U.S. involvement in the exercises, as the deployment signals to Beijing that unless it reins in its unruly ally it will see an even larger American presence in the vicinity.

As Seoul considered its options, they mounted their own offensive by pummeling the North with K-9 155 mm self-propelled howitzers and scrambling fighter jets. President Obama has pledged to stand shoulder to shoulder with South Korea.