American Airlines Group Inc on Tuesday announced it has signed a deal with Qatar Airways -- a clear indication that the friction and the much-hyped separation of the two airlines have healed.

The biggest US airline also announced it is considering opening new routes from the United States to Doha and is renewing their long-stalled code-share partnership.

In a statement, American Airlines chairman and chief executive officer Doug Parker said the issues that caused the suspension of their cooperation two years ago has been addressed. "Resuming our code-share contract will allow us to provide service to markets that our clients and stockholders value," Parker said.

"We're very happy to secure this strategic alliance with American Airlines, a union between two successful airline companies with a shared purpose," Akbar Al Baker, Qatar Airways Group chief executive, said.

Baker added that the new agreement will bring together two of the biggest airline networks in the world and provide seamless connectivity to millions of passengers to new destinations. Just a couple of years ago, such a scenario would have been viewed as unthinkable as American Airlines and Qatar were embroiled in deep animosity.

Starting in 2015, the biggest carriers in the US argued that their Gulf rivals were being unfairly funded by their governments, disrupting market competition and impacting heavily on American employment, something the Gulf airline companies deny.

Time and again, top executives of US airline firms argued that Middle Eastern carriers were expanding their presence in the US by opening new routes between Europe to key US cities.

In 2017, American Airlines and Qatar -- who were then partners in the One World Airline Alliance -- began to publicly lambast each other. In an event in Europe, Baker said there's no need to travel on those "crap American carriers." A few weeks later, Qatar offered to acquire 10 percent of American Airlines.

Baker stressed that the two airlines have "moved on from past issues" and look forward to a new partnership to establish a globally-competitive alliance for their customers.

Pending government approvals, American Airlines will stamp its code on some of Qatar Airways' non-stop and connecting flights to and from the US, including Qatar Airways' hub in Doha, allowing US passengers access to more destinations in the Middle East, Asia and Africa that it does not serve.

Those regions are growing in value. Qatar can take advantage of the code-share deal to offer clients links to more destinations in the US, the world's biggest airline market.