Norwegian Group has waited two years to hear that it can fly to the US under the subsidiary name Norwegian Air International. That day has arrived. The airline received tentative approval for a foreign air carrier permit today from the US Department of Transportation, which said it made its decision with “caution and careful consideration".

The company, which operates as Norwegian Air Shuttle in Europe, has been more than patient for over two years since it asked to operate a subsidiary from several European Union countries to the US. Norwegian applied to the US DOT in December 2013. No other airline in history has waited this long for a DOT decision. Most decisions have been granted within 60 days.

The decision means that Norwegian can continue its expansion under EU Open Skies guidelines from various points in Europe to the US, including the first-ever flights between Cork, Ireland and Boston later this year at a round-trip cost of roughly $350.

Norwegian CEO Bjørn Kjos said when Cork-Boston was announced last year that once the airline won DOT approval, “it will unlock the door for these exciting new routes, which will in turn create more competition, more choice and better fares for business and leisure passengers on both sides of the Atlantic.”

Norwegian currently uses Boeing 787 aircraft on its Transatlantic flights, though it will operate 737-800s on the shorter Cork-US flights to Boston, and later Cork-New York.

US airline unions have been vocally opposed to Norwegian’s expansion, even after the carrier noted it was hiring US cockpit and cabin crews. That sentiment came through in a statement by Air Line Pilots Association President Tim Canoll. "We are extremely disappointed by the DOT's intention to permit Norwegian Air International to fly to and from the United States because it is an affront to fair competition."

While US unions and other groups have alleged lower safety standards at Norwegian, the airline has never had a fatal accident in its 23-year history, according to Aviation Safety Network.

The airline said in a statement that it continues to contribute significantly to the US economy. "Norwegian intends to continue hiring hundreds of American-based crewmembers, bring hundreds of thousands of European tourists to the United States, continue to offer the American people affordable fares and efficiently utilize an $18.5 billion order of planes from American manufacturer Boeing," the airline said.

Speaking to this issue at Routes Americas last year, former US deputy assistant Secretary of State John Byerly said, “I’m a firm believer that Open Skies and the vigorous competition it fosters are the best way to secure for American consumers, airports, and communities the benefits of more international routes, more tourists, lower prices, and enhanced quality of service.”

Norwegian currently operates from London Gatwick, Oslo, Copenhagen and Stockholm to a combination of Boston, New York, Orlando, Fort Lauderdale, Los Angeles, and, from May 12, 2016 to Oakland.