A number of unusual activities have been observed over the past couple of years near the 50-megawatt reactor at North Korea's Yeongbyeon nuclear site.
That's according to U.S.-based North Korea monitoring website, 38 North.
The reactor has never been finished, and although the purpose of these activities is unknown, 38 North says it's not likely that work on the reactor has resumed.
A hole appeared on the roof of the reactor building between Febuary and June 2018, and there's a new structure that appears to be a water tank.
Also, a new trench was built, and a building likely used for administration or support was torn down last year.