Viettel, whose $1.22 billion unit Viettel Global Investment is trading on the Unlisted Public Company Market, has also shown interest in investing in North Korea and Cuba.
"The growth seen in Myanmar is rare in the telecom market," Dung told Reuters at his office in Hanoi. "We still have room to grow there".
Myanmar, where Viettel and its local partners launched a $1.5 billion 4G network in June last year has emerged as one of the most promising markets for the company, Dung said.
The Mytel network, jointly developed by Myanmar National Holding Public Ltd and Star High Public Co Ltd, has amassed around five million subscribers, a figure which Dung said he expects to double by the end of this year.
Viettel is also in talks to buy stakes in existing telecommunication firms in Malaysia and Indonesia, Dung said, without giving further details due to the sensitivity of the deals.
The company will be the first to develop a 5G network in Vietnam, Dung said, in anticipation of rapid development of data services.
He said Viettel had earmarked $40 million for the development of its own 5G chipset, but was also considering using technology from Ericsson and Nokia.
The military-run firm, formally known as Viettel Group, has around 60 million subscribers in Vietnam and over 30 million users across 10 other countries - predominantly in Asia and Africa.
The company is also in talks to buy a 20 percent stake in a European mobile carrier, Dung said, without elaborating.
Dung said Viettel plans to stop expanding its investment in the African market, however, where the company has struggled to make a profit due to poor economic growth.
Closer to home, Viettel is looking to invest in North Korea, said Dung, where Koryolink - a joint venture between the North Korean state and Egypt's Orascom Investment Holdings - has amassed millions of subscribers since its 2008 launch.
"We first sought permission from North Korea to build a mobile network there in 2010," he said. "But we're still waiting for sanctions to be lifted and for the country to open its market to foreign investors". - Reuters