The Vietnamese government knows that it “must avoid upsetting China” while staying open to defense ties with the United States, said Jonathan Spangler, director of the South China Sea Think Tank in Taipei.

“For Vietnam, regional stability is closely tied to national security,” Spangler said. “Vietnam, like other rival claimants, needs to balance the benefits of its economic ties with China and the political risks of not defending its sovereignty claims and thus appearing weak domestically.”

http://www.voanews.com/a/vietnam-seeks-stronger-china-ties-despite-island-buildup/3731681.html

From interview transcript:

“For Vietnam, regional stability is closely tied to national security. The Vietnamese government knows that it must avoid upsetting China while at the same time keep its options open in terms of defense ties with the US.

The Trump administration’s unpredictability introduces new variables into Vietnam’s policy considerations for the South China Sea. The Vietnamese government should ensure that US policymakers clearly understand Vietnam’s importance for maintaining regional stability while continuing to emphasize mutual economic benefits in its discussions with Beijing.

Vietnam, like other rival claimants, needs to balance the benefits of its economic ties with China and the political risks of not defending its sovereignty claims and thus appearing weak domestically.”