Denmark and Sweden both stepped up border security at the beginning of the month following the backlash in several Muslim countries in response to public desecrations of the Quran in the Scandinavian countries.

But neither country had raised its specific terror threat level until Thursday, when the step was taken by Stockholm but not Copenhagen.

“I have today made the decision to raise the terror threat level from an elevated to a high threat. We’re moving from three to four on a five-point scale,” Charlotte von Essen, head of the Swedish Security Service (Säpo), told a press conference.

But PET, the equivalent of Säpo in Denmark, is retaining its current terror threat rating, which was already at four out of five, the security service confirmed to news wire Ritzau.

“The terror threat against Denmark and against Danish interests abroad has been at the level ‘serious’, which is four out of five, for a number of years. That is equivalent to the level that Sweden is now going up to,” PET said in a written comment.

The agency has previously said that the threat level against Denmark had been “sharpened” by the Quran burnings and their fallout, but not to the extent that the terror threat level should be raised to five, termed “very serious” by PET.

Earlier this week, Denmark’s Justice Minister Peter Hummelgaard said the government was “taking seriously” a call by terror group al-Qaida for “revenge” attacks on the two Nordic countries over the Quran burnings.

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After the the al-Qaida statement was issued — but before Säpo raised the threat level in Sweden — PET said it was monitoring the situation closely.

“PET is aware of the call to action [by al-Qaida, ed.]. There is no doubt that the recent Quran burnings in Denmark have resulted in significant negative attention from militant Islamists and others, which affects the threat level in Denmark and for Danish interests abroad,” the agency told Ritzau.

“PET is following the current situation closely and will continuously assess what this means for the overall threat level and will implement any necessary security measures. This will be done in close consultation with relevant authorities in Denmark and abroad,” it said.

PET’s definitions of the terror threat level describe level five or ‘very serious’ as a “specific threat” with “capacity, intention, planning and possible implementation”.

Level four, or a ‘serious’ threat entails “a recognised threat” with “capacity, intention and planning”.

Sweden last had a terror threat level of ‘four’ in 2016, which reflects a difference in criteria applied by authorities in each country to their scales.

For Sweden to move to level four, there must be deemed a specific threat from an actor that has the intention and capacity to carry out an attack, according to Swedish news wire TT.

When Sweden was last at level four in 2015-2016, Europe had received threats from the Islamic State (Isis) terror group and the country was taking in a higher than usual number of refugees.

“PET is naturally in close contact with the Swedish authorities and is following the situation as it develops and assessing how it affects the overall threat level in Denmark,” PET said on Thursday.