Last week South Korea accused the North of sinking one of its warships. Now, one U.N. commission is investigating whether the communist state violated an agreement that it would not engage in any attacks.

United Nations Command's Military Armistice Commission is investigating whether North Korea violated an armistice agreement by attacking a South Korean warship.

15 representatives from 11 countries started the investigation by examining the evidence provided by South Korea's defense ministry.

Tensions have escalated on the Korean peninsula after South Korea accused the North of sinking the South Korean Cheonan warship with a torpedo.

South Korea has banned all trade, investment, and visits with North Korea.

The United States, which has 28,000 troops on the peninsula, threw its full support behind South Korea and said it was working hard to stop tensions from escalating.

North and South Korea are still technically at war since the Korean War ended in a truce without a peace treaty.