A U.S.-based Web site monitoring North Korea has observed low levels of activity at the North's Sohae Satellite Launching Station in Dongchang-ri. 

38 North said on Thursday that recent commercial satellite imagery indicates no new movement around the engine test stand or launch pad at the North Korean missile site since March 8th.

However, the Web site said low levels of activity have been observed at other areas, which suggest continued improvements to the missile site.  

38 North said the construction of new workshops or engineering areas at the "Horizontal Assembly Building" were first observed in September and that the roofs appeared to have been completed by April 18th. 

It added that interior work may be ongoing, while material and debris remain in the courtyards and block the exit.