Deputy CEO of Vietnam Airlines Le Hong Ha, left, and Senior Vice President - Alliances Perry Cantarutti sign the code-sharing agreement in Atlanta. (Photo Vietnam Airlines)

This is a new step of the two airlines since the US Federal AviationAdministration (FAA) granted Category 1 aviation safety rating to the CivilAviation Authority of Vietnam in February this year.

Under the agreement, the two firms will check operation systems next month.After the Vietnam Airlines' system is assessed to be at operational standard,Delta will deploy ticket sales for flights operated by Vietnam Airlines betweenHanoi and Tokyo to serve passengers who needs connecting flights to the US.

Vietnam Airlines said it’s the first step for it to explore the Vietnam – USaviation market.

Last year, Vietnam Airlines and Delta received nearly 18,000 visitors from cooperationbetween the two firms, mainly passengers travelling from the US to Vietnam.