Kabul , Afghanistan ( CNN ) -- Afghan President Hamid Karzai made an unannounced visit to Marjah on Sunday to see the gains made after a massive military offensive by Afghan and international troops to wrest control of the southern city from the Taliban . Karzai toured the city in Helmand province with Gen. Stanley McChrystal , the U.S. commander in Afghanistan . Marjah residents remain skeptical of U.S. troops and the newly installed local government that has moved in and taken over , said U.S. Marine Corps Brig . Gen. Larry Nicholson , who was in charge of the Marjah offensive . They want to know what Karzai 's government is going to be able to do for them , he said . `` We are in competition every day for the confidence and support of the population -- we 're in competition with the Taliban , '' Nicholson told reporters last week . `` We have a very narrow window of opportunity here in Marjah to make that first impression and you get one shot at it , '' he said . Dubbed Operation Moshtarak , the offensive was launched last month by an international coalition of 15,000 troops including Afghans , Americans , Britons , Canadians , Danes , and Estonians . The Marjah region has long been a bastion of pro-Taliban sentiment and is where the Taliban had set up a shadow government . It is a key area in Afghanistan 's heroin trade and full of the opium used to fund the insurgency . The hope now is for the United States to persuade the locals to change their crops from poppies -- grown to produce opium for the Taliban 's drug trade -- and instead grow crops like wheat , which can help them survive and provide income as well . Nicholson said for years , the Taliban-run town had no police force . Now , the Afghan government is in the process of recruiting Marjah citizens to join a new police force that would be trained by the Marines . The general had no timetable on how long it would take to truly secure the town . Meanwhile , in Baghlan province , about 50 insurgents , including more than a dozen Taliban , were killed in fighting between two rebel groups , the province 's governor said Sunday . Some 35 fighters of the Hezb-e-Eslami , or Islamic Party , and 13 Taliban died in the fighting , which began Saturday and continued into Sunday , Mohammed Akbar Barikzai told CNN . Apparently some bystanders also were killed or wounded , Barikzai said , adding he could not put an exact number on the civilian casualties . More Afghanistan coverage on Afghanistan Crossroads blog . Hezb-e-Eslami is an insurgent group loyal to warlord Gulbeddin Hekmatyar . They are enemies of the Taliban , but it is rare that the anti-government groups fight each other . A group of 25 Hezb-e-Eslami fighters including their commander surrendered to Afghan National Police on Sunday , the governor said . Separately , two children were killed and two were hurt in an explosion while they were playing in Kandahar province , provincial spokesman Zalmay Ayoubi said Sunday . The explosive device was in a bag that blew up while the children were playing , the Interior Ministry said in a press release . The injured children were transferred to a hospital for treatment . Two NATO service members were killed in southern Afghanistan in two separate incidents on Sunday , a NATO news release said . One was killed by small arms fire and the other by an improvised explosive device , NATO said . The identities and nationalities of the service members were not immediately released , pending notification of the relevant national authorities , the statement said . Journalist Matiullah Mati contributed to this report .
Afghan president tours Kabul , site of massive operation to take control from Taliban . Next step is to gain control of NATO , the president says . Elsewhere in Afghanistan , about 50 killed in battle between two rebel groups . Two NATO service members killed in separate incidents .