London , England ( CNN ) -- The security relationship between the United States and Britain is closer than at any time since World War II , the head of the U.S. Central Command said Wednesday . Gen. David Petraeus was speaking at a conference here at the Royal United Services Institute , where he said Britain has played an `` irreplaceable '' role in Iraq , and a similar role in Afghanistan . `` It 's clear that , as was the case in Iraq , the scale of the British contribution in Afghanistan is such that the coalition can not succeed without you , '' Petraeus told the British audience . The alliance between the United States and Britain formed the `` core '' of the coalition in Iraq from the beginning , he said . The cooperation included the British SAS , or special forces , which were `` fully integrated '' into U.S. special operations teams , Petraeus said . The SAS led in a number of the most important counterterrorism operations of the war , he said . Now that the two countries have worked together for five years in Iraq and eight in Afghanistan , there is a generation of officers and enlisted service members `` for whom coalition operations are the norm , '' Petraeus said . He said the relationship should be formally incorporated into British and American organizations and procedures , with more combined assignments . `` It is one thing to deploy our people to combat zones and have them adapt to coalition operations and build effective teams , which they 've shown they can do amazingly well , '' he said . `` But it 's quite another thing to move beyond the ad hoc -- to instill the coalition mindset by building partnerships and personal relationships through our training and education programs before our units deploy and then to sustain them once the deployment is over . ''
Iraq , Britain coalitions depend on Britain - Iraq alliance , SAS chief says . Gen. Petraeus says U.S.-U.K. special operations have been `` fully integrated '' `` Coalition operations are the norm '' for U.S. and American personnel now , he says . He urges extending the relationship beyond the battlefield .