WASHINGTON (Agencies) - Subsequent to the killing of 24 Pakistani soldiers by Nato troops, Commander of the US and Nato ordered its forces in Afghanistan to avoid approaching Afghan-Pakistan border. General John Allen asked the troops to avoid the buffer zone in the border. Even as the inquiry initiated by the US military is yet to identify who is culpable, Pakistani officials insisted that International Security Assistance Force Chief Gen Allen was ultimately the 'culprit in his capacity as commander. The real facts of the incident would be known only after the investigation is over, said Ivo Daalder, US Permanent Representative to Nato, on Friday. The most important thing we have already learnt is that General Allen has ordered the troops not to approach the created buffer zone at the border in order to reduce the chances that something like this would happen in the future, Daalder said in a breakfast meeting with the Defence Writers Group here. Giving his brief of the incident that has plunged the US-Pakistan relationship to an all-time low, the US Ambassador said the most basic fact is that there was a strike that killed 24 Pakistani border guards. What we dont know the sequence of events that led to that and we have conflicting stories. Our side of the story is still being investigated in great detail. General Allen took the responsibility immediately not only to investigate the incident but also to bring in US, Afghan, Nato and asked Pakistan to participate in the investigation, he said. The Pentagon said on Friday that Pakistan has declined to participate in the investigation. I dont know the sequence of events. There may be people who know, but so far they havent come to any conclusions and I think the best thing to do is to let the facts speak for themselves. Once these facts would come out, we will learn about the incident, Daalder said. It is clear that relationship with Pakistan has not improved. The relationship has been on the US level difficult for some time, we had the arrest of (CIA contractor) Raymond Davis (in Lahore), we had the Osama bin Laden raid (in Abbottabad) and others and finally this incident just escalates a set of differences that are real, he said. The US is trying to work together with Nato as well as other countries, understanding that this is a major problem for it, Daalder said. We need to find ways to continue cooperative effort with Pakistan. We have no choice but to cooperate with Pakistan given that the terrorists are a threat to all three of our countries (US, Pakistan and Afghanistan). As such an effective cooperation would remain essential which is why, we talked at the highest level...to try to find ways to get cooperation, he said.