Days before Afghans go to the polls to cast ballots in historical presidential elections, US President Barack Obama warned the fight in the country will be long and difficult.
Speaking to the Veterans of Foreign Wars in Phoenix, Arizona, Obama said the US must remain committed to Afghanistan's security future as well as the development of its economy and government.
"There will be more difficult days ahead," Obama said. "The insurgency in Afghanistan didn't just happen overnight. And we won't defeat it overnight. This will not be quick. This will not be easy."
The conflict is among Obama's top foreign policy priorities as he winds down the war in Iraq and steps up US efforts in Afghanistan. US Marines last month launched a major assault against the Taliban in Helmand province.
The increase in fighting has taken the largest monthly death toll of American solders since the beginning of the war in October 2001.
"The fighting has been fierce," Obama said. "More Americans have given their lives."
Afghans will vote in elections on Thursday as incumbent President Hamid Karzai continues to hold a lead in surveys, although he is expected to be strongly challenged by two rivals.
The top US commander in Afghanistan, General Stanley McChrystal, is due to report on the situation in Afghanistan after the elections. His report will not include a request for additional troops, Defence Secretary Robert Gates said last week.
The size of the US presence will near 70,000 once Obama's previously ordered buildup is complete later this year.