Special operations forces from the United States and Vietnam are signaling a readiness to start forging ties should their governments choose to do so, in what would be a major step in relations between militaries that were at war 4-1/2 decades ago.

Rear Admiral Colin Kilrain, who leads U.S. Special Operations Forces in the Asia-Pacific region, told Reuters in an interview that he met the commander from Vietnam's elite forces on the sidelines of a conference in Tampa, Florida, this week.

"Both of us would like to deepen the relationship but we're also very mindful that we go at the pace of what our governments want to do," Kilrain said, disclosing the details of the meeting.

The talks, which lasted about half an hour on Wednesday, came two days after U.S. President Barack Obama ended the U.S. arms embargo on Vietnam during a visit to that country on Monday.

Obama's trip to Vietnam, which borders China, underscored shared concerns about China's growing military clout as Beijing aggressively advances sovereignty claims to the South China Sea.

Ready for next steps

"We were both very encouraged by the positive meeting that President Obama had with the Vietnamese. And we wanted to go back and tell our chains of commands that ... we stand ready to take the next steps," Kilrain said.

U.S. President Barack Obama (3rd R) and his Vietnamese counterpart Tran Dai Quang (2nd R) review an honour guard during a welcoming ceremony at the Presidential Palace in Hanoi, Vietnam May 23, 2016.

Still, Kilrain was emphatic that the extent and pace of any such contacts would be decided by their governments.

"We will wait for positive signs from our own governments to move forward," he said.

The U.S. Navy has already taken important steps, carrying out four port visits last year, a spokesman for the U.S. Navy's Pacific Fleet said. The head of U.S. military forces in the Asia-Pacific earlier signaled to Congress his desire to do more visits in 2016.

The United States has also contributed over $92 million since 1993 to help Vietnam address the threats posed by unexploded ordnance from the war and is supporting Vietnam's development of a peace keeping training center near Hanoi, the White House said.

Kilrain noted that when it came to kick-starting military ties, elite U.S. special operations forces, which include everything from Navy SEALs to the Army's elite Delta Force, are often some of the best options.

Green Berets, who specialize in irregular warfare, were active in the Vietnam conflict.

"For us, because we're light, we're small and we can move quickly, we're about re-establishing friendships and relationships," Kilrain said.

"And we're oftentimes the easiest ones to start with militarily. And I'm proud of that."

Although he declined to speculate on first steps with Vietnam, Kilrain acknowledged the process usually started slowly, with planning conferences to share information about how their militaries were organized and discussions on human rights.

"So it's somewhat benign and it's not necessarily classic military-type training," he said.