But previous unsuccessful attempts in 2006 and 2009 took place at the Tonghae site, which is also known as Musudan-ri.

BBC: North Korea 'upgrading rocket launch site'

There has been recent activity at the older Tonghae launch site on its northeast coast, although it's unclear to what end.

NPR: US Institute: All Quiet At NKorea Test Sites

"Important progress" had been made at Tonghae Satellite Launching Ground since October 2012, the analysis from the 38 North website said.

BBC: North Korea 'upgrading rocket launch site'