Speaking to Swedish Radio News, Bildt says: "No democratic state can tolerate illegal, armed groups taking over police stations and administrative buildings. Every democratic state has to rule with the instruments that are at its disposal".
He adds that this includes the right to use violence, saying the police always has the right to use violence, even here in Sweden.
"To be able to maintain the rule of law you also have to have the possibility to use violence", Bildt adds.
At the EU Foreign Ministers meeting in Luxemburg today another four Ukrainians have been placed on the sanctions list, and the ministers will also be discussing what further pressure can be placed on Russia.
"These attempts at destabilisation are coming from Russian interests and groupings", Carl Bildt told Swedish Radio, "it is they that are using armed force to take over police stations and take the power in parts of Ukraine. If any de-escalation is needed then it should come from the Russian side. There is a large concentration of Russian troops along the border, and they still have a formal mandate from the Council of the Federation to invade Ukraine. If we are to defuse the crisis, Russia has to withdraw that mandate, start withdrawing its troops and disassociate itself from the illegal armed troops inside Ukraine."
In Kiev, Swedish Radio's foreign correspondent in Ukraine, Maria Larsson Löfgren, says to Radio Sweden says that it is hard to say whether the current situation will lead to armed conflict.
"The question is whether there will be the same type of occupation of buildings in other cities, which means that central government will have a big problem."