Hashim Thaci promised to NATO in 2013 that the KSF will not go to the north of Kosovo "without the consent of KFOR," Radio Free Europe said it learned. NATO sources explained that there was an exchange of letters between the-then Prime Minister Hashim Thaci and former Secretary General Andreas Fogh Rasmussen. "Basically, then prime minister Thaci took an obligation that the KSF (Kosovo Security Force) would not go north of the Ibar River without an agreement with the KFOR commander," one NATO source explained to RFE. This source has confirmed that the document has never been published because nothing had been signed. "It's not an agreement. It is a private exchange of letters between then Prime Minister Thaci and the-then Secretary General Rasmussen," this official exlpained. According to this source, this exchange of letters took place in the period after the Brussels agreement was reached and before the dialogue was relaunched (2013). NATO Secretary General Jens Stoltenberg has on two occasions in the last two days told Kosovo authorities that the KSF cannot cross into the northern part of Kosovo "without the consent of the KFOR commander." According to Stoltenberg, the Brussels agreement "clearly states that the KSF cannot go to the north without the consent of the KFOR commander." No article of the Brussel agreement applies to the issue of the KSF, RFE writes. This was indirectly confirmed by Maja Kocijancic, an EU spokesperson, when asked to explain which article of the agreement is related to the KSF. "The Brussels agreement concluded in April 2013 envisions the integration of security structures in Kosovo and the obligations of parties in it. The European Union expects Kosovo to continue fulfilling its obligations under the security arrangements of this agreement and according to the international military presence," Kocijancic said in a written response. KFOR spokesman in Kosovo, Vincenzo Grasso, on the other hand, claims that an agreement banning the arrival of the KSF to northern Kosovo is part of the Brussels agreement. "In 2013, an agreement was reached on the engagement of the KSF. Under the agreement, the KSF must be authorized by the KFOR commander before any deployment in the north of Kosovo," Grasso said. However, as officials at the headquarters of the alliance explained to RFE, when it comes to the Brussels agreement in the context of KSF, NATO officials have in mind the exchange of letters between former NATO Secretary General Andreas Fogh Rasmussen and the-then Kosovo Prime Minister Hashim Thaci, and not the Brussels agreement which was achieved by the-then prime ministers Ivica Dacic and Hashim Thaci. The issue of Kosovo Security Force was launched recently at NATO headquarters after the decision of the Kosovo Assembly to transform these armed forces into the Kosovo army. Kosovo President Hashim Thaci told reporters last week he sent a new letter to NATO headquarters, whose content he refused to reveal. However, several sources in the alliance told the RFE they were not aware that any letter had been received from the Kosovo President's Cabinet by the NATO headquarters. The decision to form the Kosovo army did not find a positive response from the alliance, where a discussion on reexamining relations with the KSF has been initiated.