"We will retaliate thoroughly and resolutely to provocations staged for any reasons, " the ministry's spokesman, Kim Min-seok, said.

BBC: Obama to meet South Korea's Park Geun-hye in May

"In our judgment, the missiles are short-range guided missiles, not midrange missiles such as the Musudan, " South Korean Defense Ministry spokesman Kim Min-seok said.

WSJ: North Korea Fires Another Missile Sunday

"We do not rule out the possibility of North Korea being involved, but it's premature to say so, " Defence Ministry spokesman Kim Min-seok said.

BBC: South Korea network attack 'a computer virus'