(NEWSER) – A week after the deadly—and mysterious—missile explosion at a navy testing range, Norway’s nuclear safety authority, DSA, has detected radioactive iodine in the air. DSA says its air filter station in Svanhovd, near the river that separates the two countries, detected “tiny amounts of radioactive iodine” in samples collected Aug. 9-12, CNN reports. The accident in the Arkhangelsk region of northern Russia, which killed a number of workers, happened Aug. 8. “At present it is not possible to determine if the last iodine detection is linked to the accident in Arkhangelsk last week. DSA continues more frequent sampling and analysis,” the agency said. Reuters notes that Norway’s monitoring stations detect radioactive iodine, whose source is typically unknown, around six to eight times per year.

ABC News has a roundup of what’s known and what’s not known in the wake of the explosion, which sources say likely took place during a test of a nuclear-powered cruise missile called the SSX-C-9 Skyfall by NATO or the 9M370 Burevestnik (Storm Petrel) by Russia. Russia itself has offered few details beyond acknowledging the explosion of a rocket propulsion engine using nuclear materials, at least seven deaths, and a spike in radiation levels in Severodvinsk, a nuclear submarine port 20 miles from the Nenoksa Missile Test Site. “It’s obviously not on the Chernobyl scale, but even if there is no danger and I hope there is no danger, it is very worrisome that our government acts with so little transparency,” says a Greenpeace rep. Vladimir Putin still has not said anything publicly, but his spokesperson said, “Unfortunately, accidents happen.”