( CNN ) -- NATO says a new report by the United Nations that points to a spike in violence in Afghanistan differs from the alliance 's tally because `` security incidents '' were defined differently . `` The U.N. counts a number of additional event types that ISAF does not include in its definition of security incidents , such as cache finds , arrests , assassinations , intimidation , and others , '' according to a statement Thursday from the NATO-led International Security Assistance Force . It says `` 25 % of the total U.N. security incidents are event types that ISAF does not include in its definition . '' Another difference , ISAF says , is that U.N. figures include `` all incidents regardless of which entity initiates the activity , '' while NATO counted only `` attacks initiated by insurgent elements . '' But the international force also said it recognizes that the country 's eastern regions remain a `` challenging security situation . '' Enemy-initiated attacks in June , July and August were 17 % higher than the same period in 2010 , according to the ISAF statement . The U.N. report , from the office of Secretary-General Ban Ki-moon , says security incidents in 2011 are up 39 % over the same period last year . Most of the incidents involved armed clashes and improvised explosive devices . There were just as many suicide attacks -- 12 per month -- as there were a year ago , the report says . `` The south and southeast of the country , particularly around the city of Kandahar , continued to be the focus of military activity and accounted for approximately two-thirds of total security incidents , '' the report says . But a rash of recent high-profile attacks and assassinations have raised questions about the country 's overall level of security , particularly as coalition forces are drawn down .
ISAF says 25 % of the total U.N. security incidents are not on its list . U.N. figures include ` ` all incidents regardless of which country initiates the activity , '' ISAF says . ISAF says Pakistan 's security is a security challenge . The U.N. also says monthly security incidents are up 39 % in 2011 .