"I will not say exactly how common this is, but from time to time US submarines do come into Norwegian territorial waters with such calls, upon which they are granted permission from the Norwegian Joint Headquarters, Stordal told Norwegian public broadcaster NRK.
According to press officer Ivan Moen of the Norwegian Joint Headquarters, all necessary agencies, such as the Norwegian Radiation Protection Authority, the county governor and the police, have been warned in advance in connection with the submarine visit.
"This is no ordinary commercial agreement, and no port manager can decide on it on their own. The issue must be treated politically, he told NRK.
However, discontent and distress have been on the rise among locals.
"Nuclear submarines should not be allowed to use suburban ports as supply bases," Nils Bøhmer of the international environmental NGO Bellona told news outlet Nordlys. "There is always a potential risk associated with nuclear-powered vessels. Fire and terrorist attacks are examples of events that could trigger a nuclear accident. A military base would provide greater protection against such occasions compared to a civil port," said Bøhmer, advocating that such activities be held away from densely populated areas.
"We have neither the equipment nor the trained personnel for this task. We have no facilities for decontamination, and we have not trained nuclear preparedness for several years," Mads Gilbertof the University Hospital of Northern Norway said as quoted by NRK.
According to Stordal, the Norwegian armed forced are open to political discussion. However, he argued that there was no cause for drama as the issue dealt with purely practical tasks.
With a population of over 70,000 inhabitants, Tromsø is one of world's largest cities north of the Arctic circle.