Afghan army commandos take position Sunday during a military operation in Helmand province. (Noor Mohammad/AFP via Getty Images)

Taliban fighters waged a multipronged assault Monday on the northern city of Kunduz and sought to gain footholds in the southern Helmand province, sending a pointed reminder of their resilience and reach as Afghan officials traveled to Brussels to meet with foreign donors and make a case for continued support.

The twin battles — with reinforcements called to Kunduz and U.S. airstrikes aiding Afghan forces in the south — also highlighted the struggle to keep the insurgents at bay despite the better firepower of Afghan troops and the backing of U.S. airstrikes. Most NATO forces withdrew from Afghanistan at the end of 2014.

The Afghan air force conducted several strikes over Kunduz, while U.S. military officials said they were ready to assist Afghan forces and were moving equipment and aircraft to the region. There were reports that the insurgents had overrun the city of 275,000 and that residents were fleeing. Facebook images and a Taliban video showed turbaned men with weapons walking in empty streets. But Afghan officials said that their forces were still fighting and that the city had not fallen.

According to police officials in Kunduz, the insurgents attacked the provincial capital from four directions beginning at midnight and battled Afghan forces through the day, cutting off the main road to Kabul. Some fighters commandeered residences for use as cover and were seen with heavy weapons on rooftops.

The attacks came on the first anniversary of a major strategic assault by the Taliban on Kunduz city, which lasted just a few days before the insurgents were driven out but was a major blow to the U.S.-backed war.

During the offensive, a U.S. aerial attack destroyed a hospital run by the aid group Doctors Without Borders, killing at least 42 patients and staff members. The Pentagon later said the bombing was an unintended attack, but Doctors Without Borders and other activist groups have called for further investigation.

The Taliban, which is active in many parts of the country and controls dozens of districts, has carried out new attacks across Kunduz province in the past two months.

Hundreds of miles south, meanwhile, Taliban forces launched an assault in Helmand, a desert province where they have been repeatedly attempting to take over the capital, Lashkar Gah.

The attack on the nearby Nawa district included explosions, among them a suicide truck bomb that sheared off the facade of the local police headquarters, officials said.

The town’s police chief, Ahmad Shah Salim, was killed, and many officers reportedly abandoned their posts as about 20 insurgents fought their way into the town.

While Afghan troops maneuvered to retake the town, American forces carried out airstrikes and fought using Apache helicopter gunships, U.S. military officials said.

The insurgents quickly tweeted pictures of their victory, and U.S. army advisers in Helmand urged their local counterparts to use social media to show they had not abandoned the center.

“We were 10 minutes behind, but we’re getting there,” said one army officer at Camp Shorab, a base for U.S. forces in Helmand.

Also Monday, Taliban officials issued a detailed statement criticizing the international donors’ conference planned for Tuesday in Brussels, where the Afghan government hopes to win commitments of future aid and political support by showing it has made progress on governmental reforms, economic development and efforts to bring peace.

In the statement, the Taliban said that such conferences, held at the behest of “occupying nations,” have resulted in “astronomically widening the gap between rich and poor” and that much of the aid is embezzled by corrupt officials and contractors. 

It said the government has “no constitutional legitimacy” because it failed to hold promised elections by September amid ongoing disputes between President Ashraf Ghani and his governing partner, Abdullah Abdullah. Before giving any aid, the Taliban document said, foreign donors should first “decide on ending the occupation. Withdraw troops and killing machines from our beloved homeland,” it demanded. 

“There is no doubt that the Taliban have been able to step up their attacks this year because of internal differences in the government,” said Saleh Mohammed Saleh, a legislator from Konar province, east of Kabul. “The Brussels meeting is very important for Afghanistan, and the Taliban seem to want to show that this system is weak and incapable and they are strong.”

Afghan officials are hoping that a peace agreement signed last week with Gulbuddin Hekmatyar, a fugitive Islamist militia leader who had been fighting the government for years, will help bolster its peacemaking credentials in Brussels after months of efforts to negotiate with the Taliban collapsed last year.

The agreement offers Hekmatyar full immunity for alleged past war crimes and full security to return to Afghanistan as a civilian and participate in politics. In return, officials are anticipating that he will help persuade Taliban leaders to return to the negotiating table. Hekmatyar has called on all government opponents to follow a path of peace and asked the government to release some Taliban prisoners as a goodwill gesture.

But the Taliban has denounced the agreement and labeled Hekmatyar a criminal and turncoat for making the pact with “occupying forces.” In an article on the group’s website, Taliban officials said he would “face the wrath of Allah for leaving jihad,” although they did not mention him by name.  

Gibbons-Neff reported from Helmand province.