Lori Robinson
General Lori Robinson is the first combat commander in US military historyUS DoD

A woman has been chosen to lead a key combat unit for the first time in American history. Lori Robinson, 56, a four-star Air Force general, has been nominated to take charge of the first line of defence of any invasion of the US mainland – the United States Northern Command.

The move makes her one of the top generals in the largest military force in the world, and the most senior woman in US military history, subject to formal approval by the US Senate.

Robinson enrolled in the US Air Force in 1982 and has racked up more than 900 hours of flight experience during a career that has seen her work as a flight instructor, an air battle manager and a tactical officer. Her current command, which she assumed in 2014, saw her take command of the Pacific Air Forces in Hawaii, making her the first female four-star commander of combat forces.

American defence secretary Ash Carter made the announcement on Friday, who said she "has very deep operational experience, is now running the air forces in the Pacific, which is a very challenging place for the Air Force and a very intense operational tempo".

"General Robinson, it just so happens, would be the first-ever female combatant commander," he said. "That shows yet another thing – which is that we have, coming along now, a lot of female officers who are exceptionally strong. And Lori certainly fits into that category."

United States Northern Command, known as USNORTHCOM, oversees the defence of the entirety of the North American continent's airspace. It was founded in 2002 in the wake of the 9/11 attacks, and would coordinate the US's primary defence in the event of a mainland invasion. Its mandate encompasses the US, Canada, Alaska, Mexico and the closer portions of the Carribean.

Robinson's appointment comes just a few months after secretary Carter opened up all combat roles in the US military to women in December. Women are now able to hold roughly 220,000 more jobs in the military than previously.

"America's force of the future," he said at the time, requires the "broadest possible pool of talent".