Afghan officials Thursday welcomed President Obama’s announcement that 33,000 U.S. troops will be withdrawn from Afghanistan by the end of next year, and expressed confidence that Afghan forces will be able to take over the job of securing the nation even as conflict with Taliban insurgents continues to rage.

But opposition figures, local officials and Afghan citizens cited a variety of concerns about the withdrawal plan. Some said they feared the Taliban would be reinvigorated with help from next-door Pakistan. Some worried that U.S. aid and projects would dry up, and some suggested the Afghan government is not yet strong or competent enough to assume full control of the state.

Afghan President Hamid Karzai, who recently has been highly critical of U.S. and NATO forces, said he welcomed and supported the announcement as an opportunity for Afghans to take charge of their own security. “This soil can only be protected by the sons of Afghanistan,” he told a news conference. “I congratulate the Afghan people for taking responsibility for their country into their own hands . . . Today is a very happy day.”

The Defense Ministry issued a similar statement, saying there should be “no concern” that Afghan forces are not ready to take over. A new national army and police force have been formed, trained and equipped with NATO and U.S. assistance over the past nine years.

U.S. Ambassador Karl Eikenberry, on a day-long tour of eastern Nangarhar Province, sought to reassure local officials, tribal elders and shopkeepers that the announcement of a major U.S. troop withdrawal “does not mean the United States is abandoning Afghanistan.”

“For nine years, the international community has been in front. Beginning now and over the next three years, the Afghan people will be in front,” he told a group of elders in the Mohmand Dara district. Although Afghan police and soldiers are expected to take full control of security by 2014, he said, “if you still want our support, we will still be here to help.”

Later, at a news conference in Jalalabad, the provincial capital, Eikenberry said some Afghans had asked what would change as a result of Obama’s announcement. “I tell them nothing has changed. We have a continuing commitment to Afghanistan and the Afghan people,” he said. “We seek a long-term partnership and an enduring friendship.”

At several stops, local leaders thanked Eikenberry for American assistance in building roads and improving agriculture, but they expressed worries that the problems of poverty, unemployment and lack of electricity would become worse once the United States begins to reduce its aid programs as well as its military role.

“We stopped growing poppies, and now we are growing vegetables, but it is hot here and we have no way to keep them cold,” one community leader in Mohmand Dara told Eikenberry, asking whether the United States would help finance a refrigeration plant for onions. The envoy demurred but said most U.S. aid would now be shifted to Afghan government programs rather than ended.

“I hope the next time I come here, we will be talking about onions instead of insurgents,” he said.

While expressing cautious hopes for a peaceful end to the conflict with the Taliban, Eikenberry expressed concern about havens for the Taliban and other anti-Afghan insurgents inside Pakistan. Nangarhar is a border province, and its inhabitants are especially vulnerable to insurgent predations.

“Afghanistan cannot enjoy security and stability until the terrorist threat from sanctuaries in Pakistan has been addressed,” he said. He said he regretted that the U.S. government had “underestimated the danger” posed by these insurgent havens, but he said the United States “remains absolutely committed to working with Afghanistan and Pakistan to address this threat.”

In Islamabad Thursday, a spokesman for Pakistan’s foreign ministry said the government has “ongoing engagement on issues of peace and reconciliation in Afghanistan and counter-terrorism.” It said the issues would be discussed at a regular meeting of Pakistani, Afghan and U.S. officials in Kabul next week.

The Taliban, for its part, issued a lengthy statement saying that it viewed Obama’s announcement “only as a symbolic step” because the United States seeks to build permanent military bases here and its forces are still “killing and persecuting” Afghans. “Obama and his war mongers want to deceive their nation with this announcement.”

The statement said U.S. military officials are “giving false hopes” to Americans about ending the war and that their claims to making headway in battle are “baseless claims and propaganda.” The increase in bombing, destruction and loss of life that accompanied the U.S. troop surge, it said, “cannot be called victory or progress.”

“The solution for the Afghan crisis lies in the full withdrawal of all foreign troops immediately,” the statement said. “Until this happens, our armed struggle will increase from day to day.”

The main political rival to Karzai, former foreign minister Abdullah Abdullah, said he welcomed the troop withdrawal announcement but was worried that Karzai’s government does not have the vision or capacity to take advantage of U.S. assistance before both its military and civilian role here decline.

“We know the same resources will not be available for Afghanistan in the coming years,” he said. Abdullah blamed poor national leadership for having missed “golden opportunities” in the past. “Our concern is that in the coming few years, with less resources, less troops available, we might miss further opportunities.”

Some tribal and district officials who met with Eikenberry on Thursday, although most concerned about the effect of the U.S. pullback on local projects and progress, made the same larger point.

“We welcome Mr. Obama’s decision, but we need national unity and a strong government to stand against our enemies,” said Hajji Barialai, a tribal leader in Mohmand Dara.“We want peace, and we appreciate the sacrifice your troops have made,” he told the American envoy. “But there must be someone to replace them.”

Constable reported from Nangarhar. Special correspondent Javed Hamdard in Kabul contributed to this report.