US defence secretary Gates cautions against over-optimism in Afghnistan

Kabul: US Defence Secretary Robert Gates cautioned against over-optimism despite "bits and pieces of good news" from Afghanistan, warning of hard days ahead as he arrived on Monday to meet generals and President Hamid Karzai.

Hours after Gates arrived, militants demonstrated their growing ability to strike inside Afghan cities, with gunmen launching a commando-style raid in the town of Khost near the Pakistani border in the southeast.

A Reuters reporter heard a blast and gunfire, and saw smoke rising from the centre of town. An Afghan army general said two fighters were surrounded.

The Taliban have increasingly used the tactic of commando-style raids, with bombers and gunmen storming government buildings across southern and eastern towns and in Kabul.

Gates, on his first Afghan trip since US President Barack Obama's surge of 30,000 forces began arriving in the country last December, said Nato forces had recently made gains, 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 eight-year-old conflict had finally shifted.

"I don't think we should lean too far forward in reading too much into specific, positive developments," he 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 US forces will begin to draw down in July 2011, although officials stress a military role will continue beyond that date.