Afghan security forces patrol in the restive Helmand province. (Watan Yar/European PressPhoto Agency)

Local security forces control 70 percent of Afghanistan, a senior U.S. military official said on Thursday, suggesting that the Taliban and other militants hold almost a third of that nation after 15 years of U.S. and NATO efforts to secure it.

Gen. Joseph Dunford Jr., chairman of the Joint Chiefs of Staff, told members of the Senate Armed Services Committee that Afghan security forces had taken more casualties “than we’re comfortable with” and said they remained behind in what was required in key areas including air power, special operations and intelligence.

The U.S. military did not immediately provide figures for how many Afghan soldiers and police have died as they battle a still-powerful Taliban.

“On balance, I would call what is going on right now between the Afghan national defense security forces and the Taliban [as] roughly a stalemate,” Dunford, who commanded U.S. and NATO forces in Afghanistan from 2013-2014, told lawmakers.

Dunford also said that Afghan security forces would likely be able to secure the country if they receive continued support from the United States and its partners. Even though its combat role is officially over, the U.S. military has repeatedly expanded its mission in Afghanistan to ensure that local forces can beat back militants.

The general’s gloomy assessment comes as the Afghan government struggles to hold off a series of offensives from the Taliban. Earlier this month, militants entered the capital of Uruzgan province, southwest of Kabul, in a reminder of the group’s power to overwhelm local forces even in urban areas. Roughly a year ago, the Taliban briefly took over another provincial capital in the country’s north.

The group has shown itself to be a potent adversary amid Western nations’ gradual military drawdown from Afghanistan, threatening key territory and raising questions about the country’s long-term stability. The Afghan government is also struggling to contain the sudden growth of a local Islamic State affiliate and face off against a small but resilient al-Qaeda presence.

Bruce Riedel, a former senior CIA and White House official, said the admission that the Taliban may control 30 percent of the country was “startling.”

Even if that figure is what Riedel called “the upper limit” of any credible estimate of the government’s grip, he described it as a “pretty significant indication of how big a challenge we’re facing.”

In a reminder of the still-unsettled situation there, the Afghan government on Thursday signed a deal with a political party whose leader is blamed for much of the violence that destroyed much of the Afghan capital in the 1990s.