|The White House is preparing to release a review of strategy in the conflict against the Taliban and al-Qaeda [AFP]
Barack Obama, the US president, has made a surprise visit to US troops serving in Afghanistan, but he has been criticised for cancelling a face-to-face meeting with Hamid Karzai, his Afghan counterpart.
The trip to Afghanistan, Obama's second during his presidency, came as the White House prepares to release a review of strategy in the conflict against the Taliban and al-Qaeda.
The US president was met by General David Petraeus, the commander of US and Nato troops in Afghanistan, and Karl Eikenberry, the US ambassador in Kabul, as he arrived at Bagram Air Base on Friday, before heading to the hospital to meet wounded soldiers.
However, the trip was cut from the planned six hours to just four hours with the explanation that winds of more than 70kph and heavy clouds prevented him from taking the short helicopter ride to the presidential palace in the capital, Kabul.
Obama spoke by telephone with Karzai, after the weather also made a video conference impossible.
The visit comes after the leak of US diplomatic cables that included disparaging portrayals of Karzai by US officials and others that describe senior Afghan ministers criticising the Afghan president.
"The White House is saying this trip has been planned for a month," Al Jazeera's Patty Culhane, reporting from Washington, said.
"They are saying that he wanted to go sometime between the Thanksgiving holiday here in the US and the Christmas holiday.
"They are dismissing that it has anything to do with the WikiLeaks leaks or the strategic review."
Ben Rhodes, a White House aide, told reporters on the presidential plane Air Force One there was "no major new piece" of news that would emerge from Obama's discussions with Karzai, but that he would be gathering information for the strategy review, which will be made public later this month.
"Above all, we wanted to underscore their sacrifice at a time of year when Americans are coming together as families to mark the holiday," Rhodes, a deputy national security adviser for communications, said.
In a speech to about 3,500 mostly-US troops at the air base, Obama paid tribute to the sacrifices of serving troops and their families back home.
"Today we can be proud that there are fewer areas under Taliban control," he said.
"We said we were going to break the Taliban's momentum and that's what you're doing, you're going on the offence, tired of playing defence."
'Concern and anger'
Al Jazeera's James Bays, reporting from Kabul, said there was "some concern and some anger" that Obama was not visiting the presidential palace.
"We spoke a short time ago to a high-level source in the presidential palace and he said they actually had some journalists on hand to film a news conference with the two presidents," he said.
"This high-level source very close to President Karzai, told me that there was real concern, real anger, that the president of a country with 100,000 troops in this country wouldn't come and see the president of the host country.
"He even quipped at the end of the call: 'We don't even know who issued his visa'."
Bays said that there were "perfectly clear skies above Kabul" despite US officials blaming the weather for the snub.
The US strategic review will assess and potentially recommend changes to the strategy Obama rolled out a year ago when he ordered 30,000 additional US troops to the country.
The White House has set mid-2011 for the beginning of a military withdrawal from Afghanistan and US and Nato plan to shift responsibility for security to Afghan forces by 2014.
Al Jazeera and agencies