Boris Johnson was on a collision course with the Scottish government and environmental groups as he unveiled plans for a Northern Ireland-Scotland rail tunnel and to cut air passenger duty on UK internal flights.
The plans from the Prime Minister also included upgrades on roads across the country to improve the country‘s travel infrastructure.
Johnson wants better links between the different parts of the country to help it cope better outside of the European Union, but environmental groups said reducing air duty is at odds with climate change objectives.
The Scottish government meanwhile gas described the tunnel as a £33bn "vanity project".
"It's now time to build back better in a way which brings every corner of the UK closer together," said the PM.
"We will harness the incredible power of infrastructure to level up parts of our country that have too long been left off the transport map.
Network Rail chairman Sir Peter Hendy, said to be a trusted ally of the PM, headed the team that prepared the "Union Connectivity Review".
Johnson added: “This pioneering review by Sir Peter Hendy gives us the tools we need to deliver on our ambitions for a UK-wide transport network that encompasses sea, rail, and road.
"And I also want to cut passenger duty on domestic flights so we can support connectivity across the country."
The PM first mentioned the idea of a rail tunnel between Stranraer in Scotland to Larne in Northern Ireland in 2018.
Next steps are to get engineers to assess the feasibility and costing of a tunnel, said Hendy, which would be a similar length to the Channel Tunnel. A£20mln funding package has been earmarked to upgrade rail and road infrastructure around the proposed location.
On air passenger duty, Sir Peter said the government is keen for the UK routes affected by the collapse of Flybe last year to see flights resume.