I think the better question is...what was in the shipping container previously that contained Cesium-137? And where is that/those items now?
Exactly right.
Cesium-137 is commonly cited as a potential radioactive material for use in dirty bombs. It’s a radioactive isotope produced as a byproduct of nuclear fission in reactors, often found in medical and industrial equipment like radiation therapy devices or gauges. Its properties—emitting gamma radiation, having a relatively long half-life (about 30 years), and being available in forms like cesium chloride that can be dispersed—make it a concern for misuse in radiological dispersal devices (RDDs), or dirty bombs. A dirty bomb combines conventional explosives with radioactive material to spread contamination, and Cesium-137’s accessibility and physical form make it a candidate, though the actual radiological impact would depend on the amount and dispersal method. No confirmed dirty bomb attacks using Cesium-137 have occurred, but its potential has been noted in security and counterterrorism discussions.
“… what was in the shipping container previously that contained Cesium-137…”
Many years ago there was a case in Brazil where an old radiotherapy machine that used cesium was stolen and the core broken, releasing cesium salts, which killed at least 4 people right away.
In Mexico, there was a similar case that involved cobalt. In that case, it was mixed in with scrap metal and made into rebar and table legs.