The stakes continue to climb on the Korean peninsula and so do the warnings. The U.S. confirms that North Korea has finished fueling a missile on its east coast, and it's ready to be fired.
A South Korean military official speaking under condition of anonymity said the South is at threat level Watch Condition 2, meaning a missile launch by the north is "considerably high."
The South Korean alert follows another threat by the North that nuclear war is imminent.
The North Korean government warned foreigners in the South to take cover and warned diplomats in Pyongyang they could no longer guarantee their safety.
Meanwhile, Japanese officials say they too are on high alert and are preparing for a North Korean missile launch.
Experts believe the missile is a medium range weapon and would have the ability to reach Japan and even the island of Guam. The ballistic missile has been dubbed "Musudan" by foreign experts after the name of the northeastern village where North Korea has a launch pad.
U.S. military officials say if U.S. territory or allies are threatened, they could take steps to shoot the missile down.
The U.S. has deployed defensive missiles across the region to protect against any kind of attack. Many experts believe the threats are largely just rhetoric, and an attempt by North to scare foreigners into pressing their governments to pressure Washington and Seoul to change their policies toward Pyongyang, as well as to boost the military credentials of North Korea's young leader, Kim Jong Un.
Some South Korean experts believe the North will wait to launch the missile on April 15, which marks the birthday of the country's founder, Kim Il-Sung, Kim Jong Un's grandfather.
The Associated Press contributed to this report.