HO CHI MINH CITY, Aug. 23 (UPI) -- Vietnamese Prime Minister Nguyen Xuan Phuc said Friday he is "deeply concerned" about recent developments in a long-running standoff in the South China Sea between Vietnamese and Chinese vessels.
Vietnam accused Chinese ships of violating its sovereign waters in the South China Sea in July and claimed that China redeployed the ships, including the geological survey vessel Haiyang Dizhi 8 and its escort vessels, again this month.
Phuc made the comments at a press conference with Australian Prime Minister Scott Morrison, who is in Vietnam on a state visit, and added that the countries "agree to cooperate in maintaining peace, stability, security, safety and freedom of navigation and overflight."
Morrison chose his words more carefully, calling for nations to respect one another's sovereignty but saying that his comments were not about "picking sides."
"It's about ensuring each and every nation in this region can have confidence in its independence and sovereignty," Morrison said.
The U.S. State Department weighed in on the dispute on Thursday, with spokeswoman Morgan Ortagus issuing a statement that expressed concern over China's "interference with Vietnam's longstanding oil and gas activities in Vietnam's Exclusive Economic Zone (EEZ) claim."
"China's actions undermine regional peace and security, impose economic costs on Southeast Asian states by blocking their access to an estimated $2.5 trillion in unexploited hydrocarbon resources and demonstrate China's disregard for the rights of countries to undertake economic activities in their EEZs," the statement said.
Vietnam's Foreign Ministry Spokesperson Le Thi Thu Hang called for China to withdraw its vessels on Thursday.
"Vietnam demands China immediately stop violations and withdraw all vessels from [Vietnam's] exclusive economic zone," Hang said at a press conference. She added that Vietnam has repeatedly contacted China regarding the issue.
The resource-rich South China Sea has long been a source of territorial disputes between China and several Southeast Asian states, including Vietnam, the Philippines and Malaysia.
China bases its claims for the waters and disputed island chains on historical rights, drawing a so-called "Nine-Dash Line" around almost the entire South China Sea.
In a ruling on a claim filed by the Philippines against China under the United Nations Convention on the Law of the Sea, the Permanent Court of Arbitration in The Hague, Netherlands, found in 2016 that Beijing's Nine-Dash Line was invalid.
China refused to participate in the arbitration hearing, however, and has continued to develop and militarize the South China Sea, building artificial islands and adding ports, runways and bunkers for weapons and supplies.
Washington has responded by sending vessels and aircraft through Chinese-claimed waters and airspace in the South China Sea on "freedom of navigation" operations, which Beijing has routinely condemned.