Additional 100 Marines headed to Afghan province to help fight the Taliban

These 100 Marines join the 300 Americans already in Helmand province.

— -- About 100 more Marines will be sent to the troubled Helmand Province in Afghanistan to help the 300 Americans who are already there advising and assisting Afghan security forces, according to U.S. defense officials.

Gen. Joseph Votel, the commander of U.S Central Command, approved the movement of the additional Marines to Helmand Province to provide protection for Task Force Southwest, one of the officials said.

Task Force Southwest is the contingent of 300 Marines assisting and advising Afghan forces in Helmand Province.

The request for the additional Marines was made by Brig. Gen. Roger Turner, the top Marine commander in Helmand Province, said another defense official.

Turner's request would provide "an increased capability," that official said.

According to the officials, sending additional Marines for force protection and enhanced security would free up the Marines already there to more fully advise and assist Afghan forces.

The additional Marines headed to Afghanistan will come from Special Purpose Marine Air-Ground Task Force-Crisis Response-Central Command (SPMGTF-CR-CC), 2,200 Marines that are regularly deployed to the Middle East.

Forces belonging to SPMGTF-CR-CC fall under Gen. Votel's command and can be repositioned anywhere in the region, including Afghanistan, to meet additional force requests.

The Department of Defense declined to comment about the decision on the record.

"We generally don’t discuss movement of forces or ongoing missions," Maj. Josh Jacques, a spokesman for U.S. Central Command, told ABC News.

A U.S. defense official downplayed the movement of the additional Marines to Helmand, characterizing it as "some personnel moving within theater," adding: "We do this all the time."

The movement of the additional Marines was first reported by NBC News on Monday.

There are currently about 8,400 U.S. troops in Afghanistan advising and assisting the Afghan security forces fighting the Taliban.

About 2,000 of those troops are involved in a counter-terrorism fight against an ISIS affiliate in Afghanistan and al-Qaeda.

Earlier this summer, U.S. officials said Defense Secretary Jim Mattis was considering ordering an additional 4,000 U.S. troops to Afghanistan, but any future deployments are currently on hold as the Trump administration debates a future strategy.

In late April, 300 Marines arrived in Helmand Province to replace a similar-sized force of U.S. Army troops that had been advising and assisting Afghan forces.

Their arrival marked a return to the same province where from 2009 to 2014, thousands of Marines had engaged in violent fighting with the Taliban, which led to heavy U.S. casualties.

All Marine forces pulled out of the province in 2014 as part of the drawdown of American military forces in Afghanistan ordered by President Obama.

U.S. Army advisers returned to Helmand Province in early 2016 to help Afghan forces that had suffered significant setbacks in fighting the Taliban.

Violence in the province has increased over the past year, with the Taliban once again controlling large areas of Helmand.