US Defense Secretary Robert Gates made an unannounced trip to Afghanistan on Monday to discuss preparations for a major military offensive against Kandahar, the country’s second largest city.

At a joint press conference in Kabul with Afghan President Hamid Karzai, Gates warned of a new round of bloody violence against the Afghan people. “People do need to understand there is some very hard fighting and some very hard days ahead,” he said. “I worry people will get too impatient and think things are better than they actually are.”

The US is in the midst of a “surge” in southern Afghanistan, under the direction of the Obama administration. The main target will be Kandahar, a city of some 900,000 people and the birthplace of the Taliban. The US is amassing troops for the offensive—so far only 6,000 of Obama’s additional 30,000 troops have arrived.

While “Kandahar has not been under Taliban control, it’s been under a menacing Taliban presence,” Gates warned. He discounted any effort to open up negotiations with sections of the Taliban until much more violence had been unleashed. Any peace deal would have to wait until opposition groups saw clearly that the odds “are no longer in their favor,” he said.

In addition to meeting with Karzai, Gates held meetings with Gen. Stanley McChrystal, the US commander in Afghanistan. McChrystal indicated that there would be a steady increase of repression in the area surrounding Kandahar over the coming months. “There won’t be a D-Day that is climactic,” he said. “It will be a rising tide of security as it comes.”

Gates’s trip was also evidently intended to preempt a visit by Iranian President Mahmoud Ahmadinejad, who had a previously scheduled meeting with Karzai the same day. Iran announced early on Monday that Ahmadinejad was postponing his visit.

Gates used his visit as an opportunity to issue new threats against Iran. En route to Afghanistan, he accused Iran of “playing a double game in Afghanistan.” He continued, “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 accused Iran of aiding the Taliban, “whether they are providing money” or “some low level of support.” Typically, he provided no evidence of such aid.

In a clear threat of aggressive action, Gates warned, “They also understand that our reaction, should they get too aggressive in this, is not one they would want to think about.” The Pentagon later “clarified” this statement, claiming it was meant to refer to US actions in Afghanistan, not a military action against Iran itself.

However, the charges are the latest in a series of moves designed to escalate pressure on Iran. Last month, US Secretary of State Hillary Clinton declared that Iran is “moving toward a military dictatorship.” The Obama administration is currently seeking to push through stronger sanctions against Iran in the United Nations, while intensifying charges that Iran is pursuing nuclear weapons.

Gates’s visit also comes a day after elections in Iraq, where the Obama administration has sought to undermine what it considers to be the more pro-Iranian faction, the United Iraqi Alliance coalition.

Plans for the new offensive in Kandahar follow the formal ending of major combat operations in Marjah, a much smaller city chosen as the first step in the southern campaign. In the course of the campaign dozens of civilians were killed, despite US claims that it was seeking to limit civilian casualties.

Over the weekend, Karzai visited Marjah, where he was besieged with complaints about the US military and corruption in the Afghan government.

The New York Times quoted the comments of one local Afghan leader, Hajji Abdul Aziz, denouncing the warlords associated with the Afghan government: “We will tell you that the warlords who ruled us for the past eight years, those people whose hands are red with the people’s blood, those people who killed hundreds—they are still ruling over this nation.”

In an indication of the disaster brought on by the US offensive, the Times added that the local officials “outlined newer complaints: Innocent farmers arrested by the Americans. No doctors. Destroyed irrigation canals. Schools and homes taken over by American troops. Other homes wrecked.”

“You have said on the radio that you want our children to be educated,” Aziz said. “But how could we educate or children when their schools are turned into military bases? The Taliban never build their military bases in the schools.”

Reports have also emerged that the new district chief picked by Karzai to head Marjah, Jajji Abdul Zahir, had previously been arrested in Germany on charges of stabbing his stepson. While Zahir has denied the reports, US and NATO officials have indicated that such criminality would be a good thing. “This country is not going to be run by choir boys,” the senior NATO official in Kabul is quoted as saying.

Gates added, “The question is, if the guy committed a crime and served the time, then does that automatically rule him out?”

The preparations for Kandahar make clear that the US is in the midst of a protracted and expanding occupation, which will have devastating consequences for the people of Afghanistan.