A North Korean patrol boat violated the sea border with the South several times Monday night and very early this morning, according to officials in Seoul.  It happened as the US and South Korea hold joint military exercises, which Pyongyang opposes and have accused of being a dress rehearsal for war.

The North Korean ship spent a few hours south of the border, coming within 23 kilometers of Baengnyeong Island.  After repeated warnings from the South, the boat eventually went back home. 

“The North Korean ship's NLL (Northern Limit Line, the maritime border) violation is seen as part of military drills,” said South Korean Defense Ministry Spokesman Kim Min-seok said.  “It is believed that (the ship) intended to test the South Korean military.”

It happened close to the spot where a South Korean Navy ship sank in 2010.  At the time, South Korea accused the North of torpedoing the ship, killing more than 40 sailors.