(CNN) -- New video broadcast on North Korean television shows a military unit carrying out live-fire drills in sight of a South Korean island.
The military exercises this week on the southwestern coast of North Korea were close to the disputed maritime border.
State television, KRT, also shows tanks repositioning and an artillery machine being prepared, overlooking waters that have seen a number of violent incidents over the years. North Korea shelled Yeonpyeong Island in November 2010, killing four South Koreans, claiming it was responding to a South Korean military drill in the area.
Fiery rhetoric accompanied the military actions.
Deputy commander Li Gum-chol said, "We will turn Seoul into a sea of flames by our strong and cruel artillery firepower, which cannot be compared to our artillery shelling on Yeonpyeong Island. We are training hard, concentrating on revenge to shock Lee Myung-bak's traitorous group and the military warmongers in South Korea."
Pyongyang has stepped up its rhetoric against South Korea's President Lee Myung-bak and his government since Kim Jong Un took over as North Korean leader last December after the death of his father, longtime leader Kim Jong Il.
The footage and fresh threats against South Korea come just one week after the United States and North Korea agreed on a nuclear deal after years of deadlock. North Korea effectively agreed to freeze its nuclear program and the United States agreed to provide 240,000 metric tons of food aid. The two sides are due to meet Wednesday to discuss the technicalities of the nutritional aid.
The United States and South Korea are currently carrying out annual joint military drills, which North Korea has condemned as a provocation. Now Pyongyang is staging its own.
The United States has long said improved inter-Korean relations are crucial for success in nuclear talks, but the recent increase in rhetoric against South Korea and its president make that appear unlikely in the short term.