Via Radio Prague (Rob Cameron):
It is difficult to know for certain, but it does seem the massive security operation currently in place in Prague is the result of arrests made last week in Norway. Four people were arrested by the Norwegian police on September 19th, accused of planning attacks on the Israeli and US embassies in Oslo. The Czech newspaper Mlada fronta Dnes claimed on Tuesday that one of them - a Norwegian citizen of Pakistani origin called Arfan Qadeer Bhatti - was in contact with an Albanian man by the name of Princ Dobrosi, who ran a Europe-wide drug business from Prague in the 1990s.
That certainly doesn't sound like "the most serious threat ever faced by the Czech Republic" as the Czech authorities are claiming, and there must be more to it than that for the authorities to have reacted in this way. Whether Dobrosi was somehow involved in a plot to attack Jewish targets in Prague remains a matter of pure speculation. Neither Norwegian or Czech intelligence services will comment on the claims.