Conflict-related civilian casualties in Afghanistan reached record high in 2016

— -- More than 11,000 civilians suffered casualties because of conflict in Afghanistan last year, the highest number recorded since the United Nations began tracking them in 2009.

Of those casualties, nearly 3,500 people were killed, according to a report released today by the Office of the Special Inspector General for Afghanistan Reconstruction (SIGAR).

The sobering statistics come more than two years after the combat phase of the United States’ war in Afghanistan, the longest war in U.S. history, came to a close, and four days after two U.S. soldiers died in combat in Nangarhar province.

Since the U.S.-led effort in Afghanistan closed in December of 2014, U.S. forces have supported the Afghan government’s efforts to fight ISIS and the Taliban in the country.

Civilians are fleeing their homes in droves to avoid harm. The report documented more than 660,000 people who fled their homes in 2016, the highest number of displacements on record and a 40 percent increase from the year before.

The Office of the Special Inspector General, which Congress authorized to oversee Afghanistan reconstruction for the U.S. government, did not immediately respond to ABC News’ request for comment.

A Department of Defense spokesman referred ABC News to DoD comments already contained in the SIGAR report, which include, “DOD IG will also continue to review and assess the Department’s efforts to train and equip Afghan National Defense and Security Forces.”

Meanwhile, the U.N. secretary general’s special representative for Afghanistan, Tadamichi Yamamoto, has also spoken on the issue for a U.N. Mission in Afghanistan report released last week.

“It is civilians, with increasing numbers of women and children, who far too often bear the brunt of the conflict,” Yamamoto said at the time. “With the so-called fighting season imminent, I appeal to all parties to take every measure possible to prevent unnecessary and unacceptable harm to Afghan civilians.”

The SIGAR report released today also paints a disturbing picture of civilian life in Afghanistan, detailing high rates of domestic violence and drug sales and use.

The U.S. government has invested $8.5 billion in countering Afghanistan’s narcotics economy, but the country remains the world’s largest opium producer, supplying around 80 percent of the world’s heroin. Afghanistan’s opium production was about 4,800 tons in 2016 alone.

“Drug use among women and children is among the highest documented worldwide, and 30.6 percent of households tested positive for some form of illicit drug,” the report read.

A U.S. Agency for International Development survey found that 53 percent of married women had experienced physical violence since age 15, and nearly one-third reported physical abuse taking place within the year before the survey. When accounting for sexual and emotional abuse in addition to physical violence, 56 percent were abused by their spouse, and 52 percent had experienced it within the year before the survey.

The Inspector General report was released the week after Secretary of Defense General James Mattis visited Afghanistan to meet with service members and Afghan President Ashraf Ghani. He was joined by the commander of U.S. forces in Afghanistan, General John Nicholson, who spoke at a news conference about their interest in defeating ISIS in the country.

“We’re going to keep going until they’re defeated in 2017,” Nicholson said. “By annihilating them here, it should be very clear to ISIS main there is no space to come to in Afghanistan.”

Nicholson has characterized the situation in Afghanistan as a “stalemate,” and said he was concerned about the high number of casualties taken by U.S.-allied Afghan National Defense and Security Forces.

He and General Joseph Votel, commander of U.S. Central Command, requested additional troops be sent to Afghanistan from the United States and NATO allies.

“U.S. and NATO leaders agree that additional troops and expanded authorities would enable their forces to provide the necessary advisory support... helping to address Afghan forces’ capability gaps, assist in essential leadership development, and allow for greater oversight of the U.S. taxpayer dollars committed to the ANDSF,” today’s Inspector General report read.

Mattis has not said whether he will recommend more U.S. troops be sent.