In an interview with tabloid Aftonbladet, the head of operations, Anders Kassman, says the attacks were planned by people living in Sweden motivated by a political interpretation of Islam.
Säpo says it stopped the attacks by surveillance and intelligence gathering.
Anders Kassman says the attacks were not planned by people who have fought in Syria. Nor that they necessarily would have been suicide bombings.
"We are talking terror attacks, that's serious enough," says Anders Kassman to Aftonbladet.