Tight security in Kabul as around 2,000 tribal elders and political leaders prepare to meet.<br/> Wednesday marks the beginning of the loya jirga - a four day grand assembly that will deliberate on the country's most pressing issues.<br/> Paramount among these is governing American involvement in Afghanistan as troops prepare to leave by the end of 2014.<br/> President Hamid Karzai told the assembly that the U.S. and NATO must agree to stop carrying out night raids on Afghan homes as a pre condition to Kabul signing a strategic partnership with Washington.<br/> Night raids, where security forces target insurgents who hide among the Afghan population, cause great resentment among ordinary residents.<br/> Karzai though also emphasised that maintaining a cooperative relationship with the U.S. was in Afghanistan's interests.<br/> The strategic partnership agreement is still under discussion between Kabul and Washington, and Afghanistan is negotiating similar agreements with Britain, France, Australia and the European Union.<br/> Simon Hanna, Reuters.