The incursion was off the coast of Gotland, around the same area an American aircraft violated airspace on July 18th. The planes were at least 10 kilometres into Swedish airspace, newspaper Dagens Nyheter (DN) revealed on Tuesday.
"This is extremely provocative behaviour," military strategy expert Stefan Ring told DN.
The Swedish Armed Forces refused to comment on the origin of the planes, but said that the aircraft were apparently interested in a Nato exercise in the Baltic Sea which involved 30 ships and 52 aircraft from 14 countries.
Over the past five years Swedish airspace has been violated 58 times, though statistics from the Swedish Armed Forces showed that the number of incursions has not increased over the past few years. But the trend appears to be heading upwards.
"However, there is definitely an increased activity when it comes to planes and ships getting closer and more frequently to Sweden's borders," Micael Bydén from the Armed Forces told DN.
Bydén refused to comment further on the details of the incident.
Military strategy expert Stefan Ring said he had not been aware of the violation on Midsummer's Eve, but found it rather peculiar.
"The plane could have been taking part in the Baltops exercise, and that the violation was a mistake," Ring said.
"But in that case I think it's rather remarkable that the Armed Forces didn't say anything about it earlier, and still doesn't want to comment on it now that it's public."
Ring's other theory was that the violation was a muscle-flexing display from Russia.