Question: What international military formation was headquarter in Helmand Province, Afghanistan?

Context paragraphs:
Helmand province campaign: The Helmand province campaign was a series of military operations conducted by the International Security Assistance Force (ISAF) forces against Taliban insurgents in the Helmand Province of Afghanistan.  Their objective was to control a province that was known to be a Taliban stronghold, and a center of opium production. <ref name="Gall/Wafa-NYT"> </ref>

Regional Command Southwest: Regional Command Southwest, abbreviated RC(SW), was an international military formation, of roughly division size, which was one of the components of the International Security Assistance Force in Afghanistan.  It was stood up on 3 July 2010 largely from an area previously in Regional Command South.  It was headquartered at Camp Leatherneck with an area of responsibility of largely Helmand and Nimruz provinces.  The United States Marine Corps provides the majority of the force headquarters.  It consisted of Task Force Helmand of the British Armed Forces (including Denmark and Estonia) and Task Force Leatherneck of the United States Marine Corps.  Provincial Reconstruction Team Helmand was also located in Regional Command Southwest.

Battle of Dahaneh: The Battle of Dahaneh was a battle in the town of Dahaneh, Helmand Province, and its surrounding areas as part of the Afghanistan War.  It began when U.S. and Afghan troops launched an Operation to capture the town from the Taliban, in the Helmand Province of Southern Afghanistan.  Coalition troops met heavy resistance, and believe the Taliban were forewarned of the incoming attack, though they were successful in securing Dahaneh.

Abedo: Abedo is a paramilitary commander operating in Helmand Province, Afghanistan.  She started out fighting at the side of her Mujahideen husband in 1979 when the Soviet Union invaded Afghanistan.  After the death of her husband in 1987, she continued fighting commanding 200 Mujahideen fighters.  After the withdrawal of Soviet forces in 1989, Abedo took to a life of peace.  But when the Taliban set fire to her shop she formed a small militia to keep peace in her region of Helmand Province.

Camp Leatherneck: Camp Leatherneck is a 1,600 acre Afghan Armed Forces base in Helmand Province, Afghanistan.  The site is mostly in Washir District and is conjoined with Camp Bastion, the main British military base in Afghanistan.

JTAC Hill: JTAC Hill - Joint Tactical Air Co-ordination - is a fort in Helmand Province, Afghanistan, originally built in 1841 by the Royal Engineers for the tactical defence of British India.  Since being strengthened, it has been used as an important strategic base in the ongoing war in Afghanistan.  JTAC Hill is the southernmost British forces' stronghold in Helmand Province, almost 100 miles south of the main British base, Camp Bastion, and just forty miles north of the frontier with Pakistan.

Siege of Sangin: The Siege of Sangin was a military engagement which occurred between June 2006 and April 2007, between Taliban insurgents and the British Army.  In the engagement the district centre of Sangin District in Helmand Province, Afghanistan, was occupied by the British forces and was completely surrounded by the Taliban fighters.  At one point fighting became intensive, causing General David J. Richards, the NATO commander in Afghanistan, to declare that Helmand province had seen the fiercest fighting involving British troops since the Korean War.  It became emblematic of the difficulty of the mission being carried out by British soldiers in Afghanistan, who nicknamed it "Sangingrad" (in reference to the Battle of Stalingrad).

Operation Moshtarak: Operation Moshtarak (Dari for "Together" or "Joint"), also known as the Battle of Marjah, an International Security Assistance Force (ISAF) pacification offensive in the town of Marjah, Helmand Province, Afghanistan.  It involved a combined total of 15,000 Afghan, American, British, Canadian, Danish, and Estonian troops; constituting the largest joint operation of the War in Afghanistan up to that point.  The purpose of which, to remove the Taliban from Marja, eliminating the last Taliban stronghold in central Helmand Province.

Lashkargah: Lashkargāh (Pashto: لښکرګاه‎ ; Persian: لشکرگاه‎ ‎ ), historically called Bost or Boost (بست، بوست ), is a city in southern Afghanistan and the capital of Helmand Province.  It is located in Lashkargah District, where the Arghandab River merges into the Helmand River.  The city has a population of 201,546 as of 2006.  Lashkargah is linked by major roads with Kandahar to the east, Zaranj on the border with Iran to the west, and Herat to the north-west.  It is mostly very arid and desolate.  However, farming does exist around the Helmand and Arghandab rivers.  Bost Airport is located on the east bank of the Helmand River, five miles north of the junction of the Helmand and Argahandab rivers.

2017 Sangin airstrike: The 2017 Sangin airstrike was an American bombing of the Sangin District in the Helmand Province in Afghanistan.  The United Nations mission in Afghanistan stated that "initial inquiries suggest that the airstrikes killed at least 18 civilians, nearly all women and children."  A spokesman for the Afghan defense ministry, Dawlat Waziri, denied the reports of civilian casualties but witnesses in the area corroborated the UN report that there were no Taliban members in the area and that U.S. troops had visited the neighborhood days before the incident.  The governor of the Helmand Province also corroborated that civilians were killed following the province's own independent analysis of the incident.  Elders from Sangin put the number of civilian fatalities higher at 22 killed.  Brigadier General Charles H. Cleveland, a spokesman for the international coalition, confirmed that the U.S. had conducted approximately 30 airstrikes in Sangin the week prior.  The airstrike was also referred to as the Second Sangin airstrike, seeing as the U.S. had previously conducted an airstrike in Sangin in July 2010 that killed numerous civilians.

Supporting paragraphs: Regional Command Southwest Camp Leatherneck
Answer: Regional Command Southwest