Many of the critics have been pointing out that it is impossible to differentiate "internal" and "external" traffic, but the FRA and proponents of the new law have been assuring everyone that they are not interested in Swedish traffic. It looks like they are probably telling the truth about that.
The law explicitly allows FRA to use any gathered intelligence in trade with other intelligence agencies (probably primarily USA, since an agreement was signed between the two countries last spring about enhanced intelligence cooperation). So what's in Swedish internet traffic that would be interesting to USA? Russian internet traffic, it turns out."