Kabul , Afghanistan ( CNN ) -- U.S. Secretary of Defense Robert Gates arrived in Afghanistan on Monday morning on an unannounced visit , as NATO-led coalition forces are pressing an offensive in the nation 's south . Gates was scheduled to meet with Afghan President Hamid Karzai and Gen. Stanley McChrystal , the U.S. commander in Afghanistan . Coalition forces are battling Taliban fighters around the town of Marjah in southern Helmand province . Dubbed Operation Moshtarak , the offensive was launched in February by an international coalition of 15,000 troops , including Afghans , Americans , Britons , Canadians , Danes and Estonians . Gates told reporters that he was going to Afghanistan to `` get an update on the campaign , not only in Marjah but the next steps as we look to spring , summer and fall . '' Long a bastion of pro-Taliban sentiment and awash with the opium used to fund the insurgency , the Marjah region has been known as the heroin breadbasket of Afghanistan and as a place where the Taliban had set up a shadow government . 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 such as wheat , which can help them survive and provide income as well . Karzai visited Marjah on Sunday with McChrystal to see what gains have been made in the military offensive . Gates arrived in Afghanistan on the same day that Iranian President Mahmoud Ahmadinejad was supposed to have visited . Iranian state-run media reported Monday that Ahmadinejad 's trip had been postponed until mid-March . `` Iran is playing a double game in Afghanistan , '' Gates told reporters on the flight to Afghanistan . `` They want to maintain a good relationship with the Afghan government . They also want to do everything they possibly can to hurt us , or for us not to be successful . '' Gates said the Tehran government `` will help the Taliban , whether they are providing money '' or `` some low level of support . '' The United States and its European allies are making a strong pitch to members of the U.N. Security Council for new sanctions that they say will be `` smart and effective '' as Iran moves forward with its nuclear program . Those proposed new sanctions reportedly would target Iran 's banking , shipping and insurance sectors . But it 's unclear whether China , a veto-wielding member of the U.N. Security Council , will support the proposals . The United States and other nations think Iran has undertaken a program to build nuclear weapons , an assertion Iran denies , saying the goal of the program is to produce domestic power .
Gates is to meet with Karzai and U.S . Commander Gen. McChrystal . The U.S. military has been in Afghanistan since the Taliban was toppled by U.S.-led forces after a decade of war. Gates arrived on same day as Iranian President Mahmoud Ahmadinejad was due . But Iranian officials said Ahmadinejad 's visit had been postponed until mid-March .