The cabinet has approved the building of a third runway at Heathrow Airport, Transport Secretary Chris Grayling told the Commons.
"The time for action is now," Mr Grayling told MPs 11 years after the original decision to expand the UK's biggest airport.
The Transport Secretary confirmed that 15% of new landing slots would go to routes linking London to regional airports, including in Scotland.
But he admitted that "even with today's announcement, a new runway at Heathrow is still some years away."
Approval presents a political headache for Foreign Secretary Boris Johnson, MP for Uxbridge and South Ruislip, who has previously said he would "lie down in front of bulldozers" to stop the proposed runway.
READ MORE: Scottish airports promised new slots at expanded Heathrow
However, it is understood that Mr Johnson has accepted the need to finally make a decision on a third runway.
Mr Grayling's announcement follows a meeting of the Cabinet's economic sub-committee, which had the final say on the Airports National Policy Statement (NPS). It was then reported to a meeting of the full cabinet.
Following a decision taken shortly after she became Prime Minister, Theresa May has allowed members of the cabinet to speak out against a third runway at Heathrow. However, following the loss of her majority in 2017, there is no margin for error in a vote that will follow on the NPS within 21 sitting days.
The Prime Minister's spokesman said that a decision had also been made by ministers on whipping arrangements, but these were not immediately made clear.
Proponents of building a third runway at the major hub say it is the best option to increase capacity and boost the national economy while being cost-effective.
However, critics warn the plan is "expensive and complex" and bad for the environment - while one group hinted legal action may be taken against the Department for Transport (DfT) over its "dodgy" handling of the process.
Alternative schemes include expanding Gatwick Airport in West Sussex. Any announcement in favour of a third runway is likely to be met with dismay by MPs from across the divide whose constituencies are already affected by Heathrow air traffic.
On Monday, Liberal Democrat leader Sir Vince Cable, whose Twickenham seat stands to be affected by expansion, branded the scheme "ill-conceived".
Meanwhile Extend the Runway, a group advocating increasing capacity by lengthening the airport's northern runway, said the DfT "lacks both expertise and attention to detail" and had not listened to its proposal.
"People should have zero confidence that the DfT have run a rigorous process on Heathrow's expensive and complex plan," the group said on Twitter.
The No Third Runway Coalition, which counts Sir Vince and Labour shadow chancellor John McDonnell among its members, said the DfT's process had been "dodgy and has favoured Heathrow Airport Ltd from the start".
"That will be proven in court, if it comes to it," they added.
The Aviation Environment Federation said it is "extremely unlikely that the Government will have been able to find solutions to key challenges related to the environmental impacts of expansion".
The group said: "The Aviation Strategy, which is being taken forward under a separate process to the Heathrow NPS, will set out how the environmental impacts of aviation nationally should be tackled, but will not be consulted upon until later this year with publication of the final strategy not expected until the middle of next year.
"The decision on Heathrow is set to be taken, therefore, in the absence of any policy on how to tackle aviation's carbon emissions, so with no clarity on whether limits on aviation growth will be needed in order to meet climate change obligations."