On Sunday, three U.S. Army soldiers were shot and wounded after an American-trained Afghan soldier opened fire at a joint-coalition base in the battle-hardened region of Helmand province.

NATO’s “Resolute Support” mission in Afghanistan confirmed the attack Sunday morning:

The Pentagon has yet to provide extensive details on the status of the U.S. soldiers injured in the shooting. According to a spokesman for U.S. Forces in Afghanistan, Capt. Bill Salvin, the three service members are “receiving medical treatment.” The attacker was killed by coalition security forces on the scene. He was an Afghan National Army officer from the 215 Maiwand Army Corps.

The attack was carried out “during a military training exercise,” according to TOLO News.

“The attack occurred around 1:30 p.m. local time at Camp Antonik in Washer District in Helmand,” reports Fox News. “There are roughly 8,400 U.S. troops on the ground in Afghanistan – more than in Iraq and Syria combined.”

The White House is currently considering a proposal to send more U.S. forces into Afghanistan in order to train Afghan troops.

“Since October, 12 Americans have been killed in Afghanistan and five Americans are currently being held hostage there,” adds Fox.

Despite former President Obama’s rhetoric about Afghanistan being the “good war” in which the U.S. could easily claim victory, the reality in Helmand province and other chaotic districts is far from peaceful.

In fact, the Taliban has taken over vast swaths of land since Obama first took office in 2009. The former president left the White House after presiding over an unprecedented resurgence in Taliban control and dominion over Afghan territory.

As The Long War Journal’s Bill Roggio explains, Sunday’s attack may have been choreographed by Afghanistan’s increasingly influential Taliban:

The Taliban has not claimed credit for today’s shooting, but did acknowledge it. Zabihullah Mujahid, an official Taliban spokesman described the Afghan solider as “an Afghan with a sense of patriotism.”

In the past, the Taliban has infiltrated Afghan security forces to carry out such strikes or convinced soldiers or policemen to turn their weapons on Coalition personnel. In 2012, Mullah Omar, the founder and first emir of the Taliban, announced that he created the “Call and Guidance, Luring and Integration” department, “with branches … now operational all over the country,” to encourage defections and strikes on coalition forces.

For comprehensive analysis on “green-on-blue” attacks in Afghanistan, read The Long War Journal’s report here.