The training mission by the Russian military took place just beyond the eastern edge of the Stockholm archipelago three years ago. It grabbed global headlines because Sweden's military was slow to react due to staff being on vacation and had to rely on help from Nato.
Several Swedish media outlets had previously speculated that the exercises also included a simulated nuclear attack, but this was never confirmed.
Now, Nato's Secretary General Jens Stoltenberg has revealed that this was indeed the case – a revelation that appears in the defence alliance's annual report.
The text, which was released last week but only widely reported in Sweden on Wednesday, also confirmed that four Russian Tupolev Tu-22M3 bombers had participated in the training exercise as well as two Sukhoi Su-27 jets.
The report suggests that a military base in Småland in southern Sweden and the National Defence Radio Establishment, the Swedish agency for signals intelligence just outside Stockholm, were the likely intended targets.
Stoltenberg's report concluded that the moves were part of a growing, worrying trend of aggression by Russia towards its western Nordic neighbour and others.
“As part of its comprehensive military rearmament, the extent of Russia's military manoevers and exercises have reached levels not seen since the end of the Cold War,” it said.
Sweden’s security service Säpo has raised similar concerns about Russia in recent months and even described the country as the biggest intelligence threat against Sweden in its 2014 annual report.
Last year the Scandinavian nation said it would invest 10.2 billion kronor in its armed forces as part of efforts to protect its territory, but the country's defence capabilities have been questioned following continued military activity from Russia in the Baltic region.
In October 2014, a foreign submarine – suspected of being Russian, although this was never confirmed – was spotted in Swedish waters just outside Stockholm. A number of Russian planes have also been spotted in, or close to, Swedish airspace over the past two years.