American and Pakistani forces both made mistakes that led to airstrikes against Pakistani posts on the Afghanistan border in November 2011, the New York Times is reporting. Twenty-six Pakistani Army soldiers were killed in the airstrikes, a Pentagon investigation has revealed. This is the first time America assumed some responsibility for the airstrikes, which further damaged the country’s relationship with Pakistan.

The investigation, which hasn’t yet been made public, concluded America’s airstrikes were an act of self-defense that was justified. Pakistani soldiers opened fire on Afghan and American special operations forces along the border first.

The Department of Defense released a statement, saying “U.S. forces, given what information they had available to them at the time, acted in self-defense and with appropriate force after being fired upon.” The investigation “also found that there was no intentional effort to target persons or places known to be part of the Pakistani military.”

However, Pakistan has insisted its forces didn’t do anything wrong, saying it didn’t fire the first shots. Senior Pakistani officials accused the U.S. of knowingly striking the border posts. They added they won’t accept anything but a complete apology from President Obama.

While the Defense Department statement didn’t include an official apology as Pakistan requested, it did say “For the loss of life-and for the lack of proper coordination between U.S. and Pakistani forces that contributed to those losses-we express our deepest regret. We further express sincere condolences to the Pakistani people, to the Pakistani government, and most importantly to the families of the Pakistani soldiers who were killed or wounded.”

Written by: Karen Benardello