Here’s a birthday no one is celebrating: As of Friday, the U.S. war in Afghanistan is 10 years old.

It has already surpassed Vietnam as the longest military conflict in U.S. history. The most discouraging part? The mission is only a little more than halfway toward achieving its goals, according to Stanley McChrystal, the former commander of coalition forces in the country.

Speaking at the Council on Foreign Relations in Washington, D.C., on Thursday, McChrystal said the United States had a “frighteningly simplistic” view of the country when it invaded, CBS News reports. Even today, McChrystal argued, the country lacks the understanding needed to complete the mission successfully.

“We didn't know enough and we still don't know enough,” he said. “Most of us — me included — had a very superficial understanding of the situation and history, and we had a frighteningly simplistic view of recent history, the last 50 years.”

Knowledge isn’t the only problem, he added. President Bush’s decision to invade Iraq was a costly diversion that has tarnished Muslims’ perception of the United States.

The most difficult task still ahead, he continued, is building a credible Afghan government that could rule the country peacefully once outside forces withdraw.

McChrystal commanded coalition forces in the country from 2009-10. President Obama fired him after he and his aides sounded off about the commander in chief and other top U.S. officials in a now-famous Rolling Stone magazine article.

His comments on the occasion of the war’s 10^th anniversary were corroborated by aid groups, who told the BBC that improvements in Afghanistan have been spotty at best. Drought, limited access to health care and schools, insecurity and corruption are some of the problems that will continue to afflict the country for the foreseeable future.

The BBC notes that U.N. figures show more than 11,000 civilians have died in Afghanistan in the past five years alone. More than 2,500 coalition troops have also been killed, most of them American.

The Guardian adds to the grim mood, writing that a forthcoming British government review of the Afghan war will report that there are “significant risks” of civil war or a Taliban takeover of portions of the country once NATO withdraws troops. The drawdown is scheduled to wrap up by the end of 2014.