The Russian planes were spotted approaching Sweden at lunchtime, but did not quite enter Swedish airspace, according to the country's Supreme Commander Sverker Göranson.
"[They] went out over the Gulf of Finland and then went southwards above the southern tip of Öland," he told public broadcaster Sveriges Radio on Thursday afternoon.
He added that the aircraft "flew provocatively close" both to Sweden's national borders as well as airspace used by other countries sending aircraft across the Baltic Sea.
According to Swedish newspaper Dagens Nyheter, the Russian planes were both Tupolev Tu-22M aircraft, which can carry atomic weapons as well as conventional bombs, but are also used for surveillance.
Jesper Tengroth, a press officer for the Swedish Armed Forces, told the newspaper that Sweden subsequently sent two JAS Gripen planes into the area to try to warn off the potential intruders.
"In practice, we said 'hey, we are watching you'," he said.
The following month a foreign submarine
was spotted in Swedish waters, although the Swedish military was unable to determine where it came from.