U.S. Defense Secretary Robert Gates arrived in Kabul on Monday to press for details from his generals on upcoming plans to broaden the fight against the Taliban and warned of "very hard days" ahead, Reuters reported.
He also signaled to Iran, whose president may visit Kabul this week, that Washington would respond if it started aggressively trying to undermine the U.S. war effort in Afghanistan -- something it has not attempted to any real extent so far.
Gates, on his first Afghan trip since the start of President Barack Obama's surge of 30,000 forces, acknowledged recent gains against the Taliban, including a push to take control of the Taliban stronghold of Marjah.
But he cautioned against reading too much into "bits and pieces of good news" on both sides of the Afghan-Pakistan border and said it was too soon to say whether the momentum in the more than 8-year-old conflict had finally shifted.
"I don't think we should lean too far forward in reading too much into specific, positive developments," Gates told reporters before his arrival.
"The early signs are encouraging. But I worry that people will get too impatient and think things are better than they actually are. There are still some tough times ahead."
Controlling expectations will be critical for Washington and its allies to maintain support for a war in which military casualties and costs are rising. Obama has said U.S. forces will begin to draw down in July 2011, but officials stress the military role will continue well beyond that date.
Gates said he would seek an update on the Marjah operation --- billed as the biggest offensive since U.S. forces toppled the Taliban in 2001 -- from Afghan President Hamid Karzai and General Stanley McChrystal, the top U.S. and NATO commander in Afghanistan.
He will also seek details from McChrystal about his vision for future operations to get full control of Kandahar, the former "capital city" of the Taliban.
A senior Obama administration official said last month the U.S. military would launch operations to take full control of Kandahar later this year, a massive undertaking that analysts see as a potential turning point in the conflict.
Gates said he would also hear from Karzai about his plans to pursue Taliban reconciliation. He has expressed hope for defections at low levels, but voiced renewed skepticism that senior Taliban leaders would be ready to lay down their arms as long as they thought they could still win the war.
"My guess is they're not at that point yet," Gates said.
"I think that more needs to be done. After all, we only have got about 6,000 of the 30,000 troops from the surge into Afghanistan at this point," he said.
Gates' visit might overlap with one by Iranian President Mahmoud Ahmadinejad, announced by Iranian media.
Gates reiterated his concerns that Tehran was playing a "double game" in Afghanistan, being friendly to the Afghan government while looking to undermine the United States.
"They do not want us to be successful," Gates said.
Still, he said the level of Iranian support to insurgents was still "relatively low" and acknowledged Tehran "could do a lot more" against U.S. interests in Afghanistan if it wanted to.
"Whether they're providing money and some low level of support, they also understand that our reaction, should they get too aggressive in this, is not one that they would want to think about," Gates said.
Geoff Morrell, the Pentagon press secretary, said Gates was referring only to possible reaction within Afghanistan.
The comments came as U.S. and Israeli officials play down the possibility of any imminent military action against Iran while U.S. officials pursue sanctions against the country over its nuclear program.
Israel cites Ahmadinejad's repeated calls for the destruction of the Jewish state as a clear sign an Iranian nuclear weapon would threaten the country's existence.