North Korea deployed 20 assault hovercraft to the Yellow Sea on Monday as regional tensions with South Korea continue. The deployment of the hovercraft, which are believed to be heading to the Goampo naval base -- situated just 60 kilometers from the sea border of the heavily fortified Demilitarized Zone with the South -- comes as both sides maintained more aggressive military postures, South Korean News Agency Yonhap reported.

"Since the North declared a quasi-war condition, every move of the North Korean army is being detected by the joint surveillance assets of South Korea and the United States," a Yonhap source said.

Kim Jong Un has ordered his North Korean troops to increase artillery along the border, while dozens of missile-loaded submarines have already been launched from naval bases around the country. Naval forces in the South, which ordinarily would be able to track the low-tech submarines with relative ease, have already lost some of the 50 submarines that were launched by Pyongyang over the weekend, Yonhap reported.

In response, the U.S. military, South Korea's ally with more than 30,000 troops in the country, is mulling the deployment of B-52 bombers and one submarine. In the event of war, the bombers would strike strategic targets such as airports and missile silos before ground troops would be committed. In addition, four U.S. F-16 jets and four F-15K jets took part in bombing drills Saturday and Sunday.

Pyongyang and Seoul have both been readying their respective militaries after border tensions during the last two weeks threatened to boil over into war. After two of its soldiers were maimed by land mines that were allegedly placed on the south side of the Demilitarized Zone, Seoul reestablished a propaganda speaker system that transmits negative messages about the Pyongyang regime. While Pyongyang denies the charge, it has said it would attack the South if the messages of propaganda didn’t stop. South Korea has demanded an apology over the land mine attack.

North Korea had threatened to attack the South at 4 a.m. EDT Saturday, but talks between the two managed to calm the war rhetoric.

This level of preparation for war is not uncommon on the peninsula. North Korea has regularly threatened to invade and destroy the South since the war between the two ended in 1953. Last week, Pyongyang said it would turn Seoul into a "sea of fire."