OTTAWA -- Prime Minister Justin Trudeau is approving Kinder Morgan's proposal to triple the capacity of its Trans Mountain pipeline from Alberta to Burnaby, B.C. -- a $6.8-billion project that has sparked protests by climate change activists from coast to coast.

Trudeau is also effectively killing the proposed Northern Gateway pipeline across northern British Columbia, but giving a green light to Enbridge's lesser-known $7.5-billion Line 3 pipeline expansion from Alberta to Wisconsin.

The Liberals had promised a decision on Kinder Morgan by Dec. 19 but decided to announce all the pipeline decisions at once ahead of a Dec. 9 meeting between Trudeau and the provincial and territorial premiers.

"(Trans Mountain) will create 15,000 new middle-class jobs, the majority of them in the trades," Trudeau told a news conference Tuesday. "It meets the strictest of environmental standards and fits within our national climate plan."

That includes 157 binding conditions set out by the National Energy Board, said Trudeau, who also noted the project would not have been approved without the government of Alberta's own carbon-pricing efforts and cap on oilsands emissions.

"We are convinced it is in the best interests of Canadians," Trudeau said of the decision.

"We've heard clearly from Canadians that they don't want to see someone trying to make a choice between what's good for the environment and what's good for the economy. They need to go together, and the decisions we've made today and leading up to today are entirely consistent with that."

The decision to close the book on Northern Gateway came as a surprise to no one. But Trudeau added a corollary: a moratorium on crude oil tanker shipping on B.C.'s north coast, something the Liberals promised in the 2015 election campaign.

"Very shortly we'll introduce legislation to make this tanker moratorium the law," he said.

Indigenous leaders and environmental leaders who spoke earlier in the day appeared resigned to the government's decision, but far from prepared to give up their fight.

"The struggle will simply intensify," said Grand Chief Stewart Phillip of the Union of British Columbia Chiefs. "It will become more litigious, it will become more political and the battle will continue."

There are no conditions under which the chiefs would have been willing to agree to the project, Phillip added.

"The risks are just too grave. The tanker traffic in Burrard Inlet will increase by 700 per cent and it's inevitable that there will be a collision in a very congested inlet."

Grand Chief Derek Nepinak of the Assembly of Manitoba Chiefs said the federal government simply doesn't have the blessing of Canada's aboriginal community to approve the project.

"They're not going to exclude us the second time. They don't have consent to come through our treaty lands without us," he said.

"Now's our opportunity to send a clear message that we demand that we're listened to. The standard of consent is one of consensus amongst our people. And I don't see a day where our people will consent to destruction of the land, to destruction of the water. I just don't see it."

Earlier Tuesday, the broad strokes of a year-long Liberal government effort to position the government between fossil fuel development advocates, indigenous groups and climate policy hawks played out during question period in the House of Commons.

Rona Ambrose, the Conservative interim leader, said it is not enough for the Liberals to approve major pipelines; it must then "champion them through to the end" in order to see that they actually get built.

NDP Leader Tom Mulcair, by contrast, accused the Liberals of a "Goldilocks approach" that has browbeat the Liberal party's own environmentally conscious, anti-pipeline MPs into silence.

Trudeau was happy to claim the middle ground.

"One side of this House wants us to approve everything and ignore indigenous communities and environmental responsibilities," he said.

"The other side of the House doesn't care about the jobs or the economic growth that comes with getting our resources to market."

The stalled Northern Gateway oil pipeline from Alberta through the Great Bear Rain Forest to Kitimat, B.C., had so far been thwarted in the courts for lack of proper indigenous consultation.

The less prominent Enbridge project will see the half-century-old Line 3 pipeline from Alberta through southern Saskatchewan and Manitoba to the United States replaced by an entirely new line about twice the current pipeline's working capacity.

The Trans Mountain and Line 3 expansions alone would boost pipeline capacity by more than 1.1 million barrels per day.

The pipeline decisions follow weeks of Liberal government announcements designed to show it is serious about combating climate change, including an accelerated coal phase-out and a national floor price on carbon emissions starting in 2018.

Trudeau confirmed Tuesday that he'll be holding a first ministers meeting with provincial and territorial premiers as well as indigenous leaders on Dec. 9 in Ottawa, where the pan-Canadian climate plan will be the main focus of the agenda.

U.S. Vice-President Joe Biden will also be making a visit to Ottawa on Dec. 8-9 to meet with the first ministers -- perhaps one last opportunity for the Liberals to showcase their environmental policy entente with outgoing President Barack Obama before president-elect Donald Trump's inauguration in January.