Myanmar has taken "positive steps" to reduce its military relationship with North Korea, the White House said ahead of a historic visit by President Barack Obama to Yangon.
Myanmar, also known as Burma, was suspected of pursuing military and nuclear cooperation with Pyongyang during long years of junta rule which ended last year.
"We've had a dialogue with the Burmese government about the need to reduce their relationship with North Korea," Ben Rhodes, a US deputy national security advisor said on Air Force One as Obama flew to Asia.
"We've seen them take some positive steps in that direction. And what we'd like to see, again, is an end to the relationship that has existed between Burma and North Korea."
Rhodes noted that Washington had also begun the early stages of a military-to-military engagement with Myanmar, and hinted that over time, the country could expect to join annual US military exercises with Thailand.
Reports of military cooperation between Myanmar and North Korea have been a cause for concern for Washington and its Asian allies in the past.
Myanmar President Thein Sein, who will host Obama in Yangon on Monday, has denied any covert effort to obtain nuclear weapons technology from North Korea, which is locked in a prolonged atomic showdown with the United States.
A 2010 United Nations report accused Pyongyang of supplying banned nuclear and ballistic equipment to Myanmar, Iran and Syria.
Myanmar has maintained that it is too poor to acquire nuclear weapons and that it has always abided by UN resolutions, even halting a Russia-backed peaceful nuclear research programme because of international concerns.
As it seeks to deepen North Korea's isolation over its nuclear programme, Washington has made intense efforts in recent years to crack down on Pyongyang's trade in nuclear equipment, expertise and ballistic technology.
Obama will become the first sitting US president to travel to Myanmar on Monday, after a first stop in Thailand.
As well as meeting Thein Sein, he will visit democracy champion Aung San Suu Kyi at the lakeside villa where she endured years of house arrest before the sweeping reform drive pioneered by Thein Sein and his nominally civilian administration.