Blog 38 North, edited by a North Korea research team at the Maryland university, early this month said its assessment of satellite imagery indicated North Korea was testing new rocket engines.
Johns Hopkins said construction at another facility was halted. Projects at the Tonghae Satellite Launching Ground were seemingly geared to supporting larger rockets. Researchers said Tuesday work at the location slowed at the end of 2012 and may have stopped altogether in May.
North Korean rocket programs put the U.S. West Coast within range. Rocket launches in 2006, 2009 and 2013 coincided with nuclear tests in North Korea.
Johns Hopkins researchers said the work stoppage may indicate North Korea shifted operations to another launching station or it has decided to halt development of larger rockets.
"Exactly why construction has halted remains unclear," researchers said.
They said if North Korea decides to go ahead with production, it would be at least a year behind schedule.
"Depending on the pace of renewed construction, the facility may not be complete until 2017," the research team said.