Stockholm, Feb 11 : Swedish police has said that they had launched an operation to bolster security in the capital Stockholm after the Security Service reported an increased number of threats against the country. Security will, therefore, be increased at "symbolically important" objects, a police source told Swedish Television (SVT) on Friday. According to a statement published on the Security Service website on Wednesday, "The reactions to the burning of a Quran outside the Turkish Embassy in Stockholm in January have been considerable." "This development means that violent Islamist circles globally are currently focusing more on Sweden," the statement said, adding that the terrorist threat level remains elevated but could be raised further "if this development continues". On February 5, the US Embassy in Sweden issued a statement, warning US citizens in the country of "possible retaliatory attacks by terrorists" and urging them to exercise caution in public venues frequented by large number of people, Xinhua news agency reported. In January, the Swedish police authorised a protest in which a far-right politician burned a copy of the Quran outside the Turkish Embassy in Stockholm. /IANS