A U.S. Army adviser from Task Force Forge conducts a room-clearing drill with an Afghan trainee to demonstrate proper tactical procedures at the Regional Military Training Center in Helmand province, Afghanistan, March 8, 2017. Fears that the Taliban could capture a regional capital this year were heightened when the insurgents recently took the strategically important district of Sangin. (Kay M. Nissen/Resolute Support)

A U.S. Army adviser from Task Force Forge conducts a room-clearing drill with an Afghan trainee to demonstrate proper tactical procedures at the Regional Military Training Center in Helmand province, Afghanistan, March 8, 2017. Fears that the Taliban could capture a regional capital this year were heightened when the insurgents recently took the strategically important district of Sangin. (Kay M. Nissen/Resolute Support)

An Afghan National Army soldier mans his position while his fire team conducts a clearing drill at the Regional Military Training Center in Helmand province, Afghanistan, March 8, 2017. The soldiers are members of the ANA 215th Corps and will fight in one of Afghanistan's most contested provinces upon completion of their initial training. (Kay M. Nissen/Resolute Support)

Two advisers from Task Force Forge demonstrate how to clear a room during security operations training at the Regional Military Training Center in Helmand province, Afghanistan, March 8, 2017. Task Force Forge is a train, advise and assist unit that supports the NATO Resolute Support mission. (Kay M. Nissen/Resolute Support)

Afghan army soldiers conduct a clearance training drill at the Regional Military Training Center in Helmand province, Afghanistan, March 8, 2017. Upon completion of training, the soldiers from the 215th Corps will go forward to support security operations in the region. (Kay M. Nissen/Resolute Support)

KABUL, Afghanistan — When the Taliban officially kick off their new fighting season within weeks, they’ll pick up where they left off last year: threatening several provincial capitals and stretching Afghan forces to their limit.

“There will be an increase in attacks in those provinces that are on the verge of collapse,” Taliban spokesman Zabihullah Mujahid told Stars and Stripes. While in the past the group had single units covering several provinces, Mujahid said: “This year, we have a unit for every province in the country.”

The ability to control the capitals of Afghanistan’s 34 provinces appears to be the barometer that U.S. and NATO forces use to measure success in the Afghan conflict. Occupying a capital has been a top priority of the Taliban, and some fear this could be the year they finally succeed.

Those fears were heightened in March, when the insurgents captured Helmand province’s strategically important district of Sangin. The takeover occurred despite a U.S. bombing campaign and the support of American special operations troops.

“The Taliban took over everything,” said Bashir Ahmad Shakir, a member of Helmand’s provincial council. “This will create threats to more districts in Helmand in the weeks and months ahead.”

NATO and Afghan military officials said Afghan forces had “repositioned the district center” in Sangin and still have a presence there. But residents say the Taliban are in control and will use the town as a springboard to launch attacks on Lashkar Gah, Helmand’s capital about 80 kilometers to the southwest, as the days get warmer.

The Taliban are now said to occupy more than half of Helmand, which produces most of Afghanistan’s opium crop and provides the insurgents’ with their largest revenue source.

Loss of territory in the province contributed to a 15 percent nationwide loss of government-held land in 2016, a year that saw nearly 6,800 members of Afghanistan’s security forces killed in action. International forces, nevertheless, have repeatedly described the 2016 campaign as successful because insurgents failed to overrun a provincial capital.

Despite the recent events in Sangin and claims of growing Taliban strength, Navy Capt. Bill Salvin, a spokesman for U.S. and NATO forces in Afghanistan, said the international coalition does not believe the insurgents will be any more successful in 2017 than they were last year.

“Our assessment is that they’re not getting stronger,” he said. “And the goal of our campaign this year will be to reduce the amount of the population that is under Taliban control and reduce the areas that are contested.”

He added: “But we think the fighting season is going to be very much like it was in 2016 — a very challenging, very difficult fight.”

Some observers believe increasing assistance from Russia and Iran could add to the difficulty. The two countries have been accused of providing military support to the Taliban, a claim both have dismissed as propaganda.

“I think it is fair to assume they may be providing some sort of support to (the Taliban), in terms of weapons or other things that may be there,” Gen. Joseph Votel, the head of U.S. Central Command, told members of the House Armed Services Committee on Wednesday when asked about Russian involvement in Afghanistan.

Russia has been open about expanding diplomatic contacts with the Taliban, saying the group should be considered a bulwark against the local branch of the Islamic State group, but it has denied supplying weapons. In February, America’s top commander in Afghanistan, Gen. John Nicholson, said Moscow’s overtures were “overtly lending legitimacy to the Taliban to undermine NATO efforts.”

“The game is becoming extremely bleak and dirty in Afghanistan,” said Ali Mohammad Ali, a former senior Afghan intelligence officer, who told Stars and Stripes that there was evidence to suggest Moscow had provided weapons to the Taliban.

“The Taliban are definitely gaining momentum from both political and military support from Russia, Iran and other countries,” he said.

But Ali added that despite this backing, the insurgents are still unable to fight Afghan forces conventionally. As long as the U.S. was willing to provide combat support to Afghan troops, he said, the Taliban would be unable to hold a provincial capital against superior coalition firepower.

NATO officially ended combat operations in Afghanistan at the end of 2014, shifting to a train-and-advise role. At that point, the U.S. was authorized to strike the Taliban only in self-defense, as the group is not considered a legitimate target under the U.S.’s separate counterterrorism mission. However, the White House in June expanded the military’s authority to conduct airstrikes against Taliban fighters to support the Afghans in critical operations.

The decision, coming amid escalating violence, was made, in part, to prevent a repeat of September 2015, when the Taliban overran and briefly held the northern city of Kunduz. That was the first time the group had captured a city since being ousted from power in 2001.

The insurgents took parts of Kunduz again at the end of last year and threatened to overtake Lashkar Gah and the capitals of Uruzgan, Farah and Baghlan provinces.

With fears growing in these and other cities as the 2017 fighting season approaches, Gen. Dawlat Waziri, spokesman for the Afghan Defense Ministry, said he wanted to assure Afghans that “government forces are ready to chase the enemy anywhere in the country that there’s a threat.”

“It will be impossible for them to capture any big city or province,” he said.

Zubair Babakarkhail contributed to this report.wellman.phillip@stripes.com