Dakota Pipeline: What's behind the controversy?

• Donald Trump's backing of the Dakota Access Pipeline project has set the stage for a new confrontation with native Americans and environmentalists 
• Trump signed 2 presidential memoranda supporting the Dakota and Keystone XL pipelines telling the army to review one, and inviting a private company to re-apply for the other
• the Dakota Access is a $3.7 billion pipeline that is planned at nearly 1,200 miles long to transport some 470,000 barrels of crude oil a day across 4 states, from North Dakota to a terminal in Illinois, where it can be shipped to refineries
• The pipeline would provide a more-cost effective, efficient means of transporting crude, rather than shipping barrels by train 
• Most of the pipeline has already been built but the section closest to the Standing Rock Sioux reservation was still awaiting federal approval
• The decision came after months of protests by the Standing Rock Sioux Tribe and their supporters, who set up a number of spiritual camps-Sacred Stone, Oceti Sakowin, Red Warrior, and Rosebud Sicangu-near the Missouri river
• They had argued that the project would contaminate drinking water and damage sacred burial sites
• The US Army Corp of Engineers suspended the project last year, but in February 2017 said it planned to grant final easement for the remaining section of the project
• Construction sites are technically just north of the tribe's reservation but the Sioux say that the government took this land from them illegally in an 1868 treaty 
• Native Americans also accused the government of approving pipeline construction without consulting them, a requirement under US law
• Environmental activists say the pipeline would perpetuate fossil fuel production
• Trump backed both projects in presidential memoranda
• Trump backed a plan to use American steel in any and all future pipeline projects
• Trump does not have the power to approve either the Dakota Access or Keystone XL pipelines, his memos offer significant encouragement
• Trump says he believes finishing the Dakota pipeline will "serve the national interest" and ordered an "expedited" review
• Trump ordered the army to "consider" withdrawing its December memo which effectively paused the project
• Trump invited TransCanada to resubmit its application on the Keystone XL project and instructed the secretary of state to "take all actions necessary and appropriate to facilitate its expeditious review"
• The Standing Rock Sioux said they would fight the decision
• Greenpeace director Annie Leonard said that "instead of pushing bogus claims about the potential of pipelines to create jobs, Trump should focus his efforts on the clean energy sector where America's future lives
• 10,000 people joined the campsites in the region
• supporters: hundreds of US military veterans, Green Party presidential candidate Jill Stein and Democratic presidential primary contender Bernie Sanders, Robert Kennedy Jr, environmental activist, Shailene Woodley, Mark Ruffalo
• A Colorado woman who shot at police trying to remove protesters from private property was arrested and charged with attempted murder 
• Police have been accused of using excessive force, including dousing crowds with pepper spray and freezing water as well as firing sound canons, bean bag rounds and rubber bullets
• officers have arrested hundreds of people and accused activists and journalists of criminal trespass, rioting and other felonies
• at one point, police held protesters in temporary cages made of chain-link which activists equated to dog kennels
• the allegations led the United Nations to speak out against the use of excessive force against protesters