North Korea has informed Japan of a plan to conduct a military exercise in the East Sea.

According to the Japan Coast Guard, the North said the drill will take place off the coast of its eastern port of Wonsan from eight a.m. to eight p.m. starting Thursday and will end July tenth.

The North says the region where the exercise will take place is 450 kilometers long and 110 kilometers wide. The area includes stretches of sea from which North Korea banned ships on two earlier occasions this month.

The Japan Coast Guard said the North designated the region as a danger zone before launching a rocket in April.

This is the first time Pyongyang has officially announced its reason for installing a ban on ship travel.