The country takes issue with the installment of a new missile defense system.
Pyongyang appeared to express its displeasure over a US plan to install an advanced missile defense system in South Korea by launching three missiles into the sea.
Aimed to knock down North Korean rockets, Washington and Seoul's missile-defense system already has its work cut out.
The Pentagon's plan to put an advanced missile defense system in South Korea might have as much to do with Beijing as it does with Pyongyang.
North Korea defied UN sanctions and launched a long-range rocket on Sunday, but what it claims is a satellite is suspected of being a hunk of space junk.