North Korea conducted live-fire drills near its disputed western sea border with the South on Tuesday.
The exercises, however, were short-lived, lasting just 10 minutes.
South Korea's Joint Chiefs of Staff said the North conducted artillery drills in two regions north of the Northern Limit Line in the West Sea. and that none of the 50 artillery shells fired, fell in South Korean waters.
South Korean residents on five nearby border islands were advised to take shelter.
Last month, during a similar drill by the North, the two Koreas exchanged fire across the maritime border, after more than a hundred North Korean artillery shells fell into South Korean territory.
Expecting such a scenario could occur this time around, President Park Geun-hye had told the South Korean military to respond firmly, should any North Korean shells land in South Korean territory.
Seoul's defense ministry beefed up its vigilance by dispatching warships and fighter jets to the area.
The fire drills come amid Pyonyang's threats of "something big and unimaginable" for its enemies before April 30th.
This, on top of a threat it issued last month to conduct a new type of a nuclear test.
Experts say a fourth nuclear test could be in the works as recent satellite imagery has shown increased activity at the regime's nuclear test site.
During a visit to Seoul last week, U.S. President Barack Obama warned that another test would only further isolate the North and said that South Korea and the United States stand "shoulder-to-shoulder" against any provocation by the North.
Hwang Sung-hee, Arirang News.