On Tuesday, President Trump signed two executive orders intended to revive the Dakota Access and Keystone XL pipelines — two controversial oil projects that had been halted under President Obama after years of grassroots protest and fierce opposition from climate activists.

While nothing’s final until the pipelines are actually built, these orders make approval much more likely. Trump has made supporting the oil and gas industry a key priority of his presidency, and this is his first big policy move toward that end.

So let’s take each project in turn, to see what these executive orders actually do:

1) The Dakota Access pipeline still faces a review from the Army Corps

The Dakota Access Pipeline is a 1,134-mile-long pipeline that would ship 450,000 barrels of oil per day from the Bakken fields in North Dakota to a shipping terminal in Illinois. It’s about 85 percent complete, save for a portion near the Standing Rock Reservation in North Dakota. For months, the Standing Rock Sioux and other activists have been protesting construction there, arguing that the pipeline could endanger both nearby water supplies and sacred sites.

The Army Corps of Engineers had originally approved the pipeline’s route near the reservation, but the Standing Rock Sioux filed a lawsuit over this decision, claiming that the tribe wasn’t properly consulted. In late 2016, the Obama administration ordered the Army Corps to reconsider its decision, and in December the agency announced that it would also explore alternative pipeline routes further away from the reservation. This would require a lengthy environmental review — and meant a big delay for Dakota Access.

Currently, the Army Corps is preparing an Environmental Impact Statement (EIS), which means exploring different potential routes for the pipeline, soliciting public comment, and so on — a complex legal process that could take a year or more.

In his executive order today, Trump told the Army Corps to hurry it up. First, he suggested that the agency might want to “rescind or modify” its decision to consider alternate routes. He also told the Army Corps to “take all actions necessary and appropriate” to review and approve the pipeline “in an expedited manner... to the extent permitted by law and as warranted.”

So what happens next? That’s really up to the Army Corps, explains Sharon Buccino, an attorney and director of the Land and Wildlife program at the Natural Resources Defense Council. The Army Corps could decide to continue with its EIS anyway, taking time to explore alternate routes. Or the agency could read Trump’s order and decide that an EIS is not required, after all — and hence rush to approve the route that passes near the reservation. If the latter happens, the Standing Rock Sioux and environmental groups would almost certainly try to challenge the decision in the DC Circuit Court.

If the former happens, and Army Corps carries out its exploration of alternative routes, it will eventually have to decide which route to approve — a decision that would have to be grounded in the facts of the EIS. Ultimately, that decision would be made by the Assistant Secretary of the Army for Civil Works and the US Army Corps of Engineers — a political position that will presumably be filled by Trump.

Bottom line: some sort of approval of the pipeline looks very likely. The big questions are what route the Army Corps settles on and how long the agency takes to decide. Trump is pressuring them to figure things out sooner rather than later.

In a statement, Dave Archambault II, chair of the Standing Rock Sioux, urged the Trump administration to let the EIS play out: “President Trump is legally required to honor our treaty rights and provide a fair and reasonable pipeline process. ... The existing pipeline route risks infringing on our treaty rights, contaminating our water and the water of 17 million Americans downstream.”

Shortly before Trump issued the order, the Standing Rock Sioux asked protesters to leave the site where they were protesting pipeline construction, noting that they need time to clean the area of debris before spring flooding began. It’s unclear if protests could resume around Standing Rock in light of this new order.

2) Trump is inviting TransCanada to renew its application for Keystone XL

The Keystone XL pipeline, meanwhile, was a proposed 1,179-mile pipeline between Hardisty, Canada, and Steele City, Nebraska, that would be built by a Canadian firm called TransCanada. It would carry up to 830,000 barrels of oil per day — mostly from Alberta's oil sands, but also some from North Dakota.

This pipeline became a major flash point for climate activists during the Obama administration — and Obama eventually rejected TransCanada’s application, ruling that the project was not in the national interest. (Because the pipeline crosses national borders, the State Department has a major say in the project.) Among other things, Obama argued that the project, which would help bolster oil sands production in Canada, would undercut America’s “global leadership” on climate change.

Trump, obviously, has no such concerns. So on Tuesday, he signed an executive order that invited TransCanada to resubmit its application for the Keystone XL pipeline. He also ordered the State Department to “take all actions necessary and appropriate to facilitate its expeditious review” — and reach a decision in no later than 60 days.

On Tuesday afternoon, TransCanada said it was preparing a fresh application for Keystone XL. Environmentalists denounced the decision, though they have far less leverage to block the pipeline this time around than they did under Obama. Note that TransCanada will have to get a number of additional permits from the Army Corps and Department of Interior to finish the pipeline, and opponents could try to challenge the project there — but this is an uphill battle.

Trump also wants to study how to build pipelines using only US steel

There’s one last odd twist: During the signing, Trump told reporters he’d “renegotiate some of the terms” of Keystone XL — possibly with an insistence that TransCanada only use American steel. (That would be a problem for the company: Only about 50 percent of the Keystone XL pipe suppliers were American, with the rest coming from Canada, India, and Italy.) But there’s nothing in the executive order about negotiating terms — and later on, Trump’s press secretary Sean Spicer said the president just wanted the pipeline approved. So this “renegotiating” bit seems to be just empty talk.

Trump did, however, sign a third executive order on Tuesday ordering the secretary of commerce to develop a plan within 180 days in which all new and upgraded pipelines inside the United States “use materials and equipment produced in the United States, to the maximum extent possible and to the extent permitted by law.” It’s unclear how this would be at all compatible with WTO rules, but we’ll see what the study says.

He also signed two other orders intended to speed up environmental reviews of infrastructure projects. It’s unclear how much practical effect those orders will have; read Darryl Fears’ breakdown for more on that.

Watch: The fight over the Dakota Access Pipeline