The new U.S. ambassador to Afghanistan says the United States is not rushing to leave Afghanistan, as international forces begin withdrawing from the war-torn country.

Ryan Crocker told diplomats that while there will be no “rush for the exits,” the U.S. is also not interested in having permanent bases in Afghanistan. He was sworn in Monday during a ceremony at the U.S. Embassy in Kabul.

Some 33,000 American troops are set to leave Afghanistan by September of 2012, as Afghan forces begin taking control of their country's security. Last week, the first seven areas of Afghanistan were transitioned from NATO control to local forces.

While Crocker acknowledged that many citizens of troop-contributing nations were weary of war, he noted the “incalculable long-term effects and cost of getting it wrong.”

The new envoy has served as ambassador to Pakistan and Iraq. Crocker came out of retirement to replace outgoing U.S. Ambassador Karl Eikenberry.

Crocker reopened the U.S. Embassy in Kabul after U.S.-led forces ousted the Taliban in 2001. In his speech Monday, Crocker vowed that the international community will not allow the Taliban to regain power in the country after 2014, when most foreign combat forces are set to leave Afghanistan.

On Monday, NATO said one of its helicopters crashed in eastern Afghanistan. NATO said as coalition rescue forces approached the crash site, they came under enemy fire. All passengers and crew members were safely transported to a nearby base.

Afghan officials say the aircraft went down in Kunar province. The Taliban claims to have shot down the helicopter as coalition troops were preparing to attack militants.

In western Afghanistan, NATO says an insurgent attack killed one of its service members on Monday.

In the south, the coalition said one of its helicopters accidentally wounded five Afghan children on Saturday while firing at an insurgent in the Nahr-e Saraj district of Helmand province. The children were evacuated to a NATO medical facility for treatment. The coalition said it was investigating the incident.

NATO said Monday it is also investigating civilian casualties in a separate incident in Wardak province. NATO says a coalition patrol struck a roadside bomb while conducting a road clearance operation in the Sayyidabad district. One civilian was killed and several coalition members wounded.

NATO says that following the bomb blast, coalition forces exchanged gunfire with insurgents, after which three civilian bodies were found and one wounded civilian was found in a vehicle. The coalition says it is trying to determine how the civilians were killed and wounded.