Australia will continue its surveillance flights over the disputed South China Sea and insists on unhindered access to the area’s trading routes, Defence Minister Kevin Andrews said.

“We have been surveilling the area for close to thirty five years,” Andrews said on Sunday in an interview on the sidelines of the Shangri-La security forum in Singapore. “We are doing it currently and we will continue to do it in the future.”

Andrews would not be drawn on whether Australia may fly planes over reefs that China has reclaimed -- a move that could amount to a “freedom of navigation” challenge. China has reserved the right to have an air defense identification zone over the South China Sea and its navy has warned planes to stay away from some areas.

“We want a de-escalation of tensions in the area,” Andrews said. “We insist upon the right to use waters, transit waters, that have been traditionally used over a long period of time.”

Australia, a longstanding U.S. ally in the region with Marines based in its tropical northern city of Darwin, is seeking to balance its concerns about China’s military rise against the need to preserve economic ties with its largest trading partner, a big buyer of the country’s iron ore. Andrews said Australia is a “good friend of China” and “we want to retain that relationship with them.”

His comments in the interview echoed remarks by U.S. Defense Secretary Ashton Carter during his speech to the Singapore forum, where he pledged the U.S. would fly, sail and operate wherever international law allows.

China this month warned a U.S. surveillance aircraft to leave a “military alert zone” after it approached reclaimed reefs occupied by China in the Spratly island area. Parts of the sea are also claimed by Vietnam, Malaysia, the Philippines, Taiwan and Brunei.

Asked if Australian aircraft would fly over the contested reefs, Andrews said: “I don’t know exactly where they are going, every mission is slightly different in terms of where it is going, but there is surveillance over the South China Sea.”

Andrews said that Australian Orion aircraft operate to the east and west of Malaysia with the knowledge of the Malaysian government and other countries in the area.

“We support the rights of all countries in the region to be able to transit international waters, to have unencumbered trade,” Andrews said. “As a trading nation that is significant for Australia,” he said. “We’re all in this together.”

Still, “as to suggestions that there is going to be some international force or something like that, I think we’re all getting ahead of ourselves at this stage,” he said.

Andrews said that China’s turning a rocky outcrop or reef into a “full airport,” while putting weapons on them, has raised tensions because it is a militarization that hasn’t occurred before. “We’re saying to all parties in the South China Sea that the reclamation activities should cease.”

The U.S. recently detected two mobile artillery pieces on one of China’s reclaimed reefs in the Spratlys, Brent Colburn, a Pentagon spokesman, told reporters on May 28 in Singapore.

Indonesia’s defense minister has raised the prospect of joint patrols of the South China Sea by the claimant nations, including China. Indonesia is not a party to the disputes.

Some senior U.S. military leaders have also advocated joint Southeast Asian patrols of the waters, though without China as a participant. The Association of Southeast Asian Nations has been negotiating a code of conduct for the area with China for years without major progress.

Asked about the prospect of patrols involving China, Andrews noted the precedent in the Straits of Malacca for joint patrols against piracy.

“We’ve taken the view in terms of operations and training and things like that the more countries involved overall in these sorts of operations that can work together the better,” Andrews said. “We want to be a nation that is friendly to China but we’re saying to everybody let’s just cool things off and de-escalate tensions.”

Australia meanwhile expects the three contenders for the contract to build Australia’s A$50 billion ($38 billion) submarine fleet will submit among their proposals a “hybrid” for both onshore and offshore production, Andrews said.

Australia has invited Japan, Germany and France to bid for the contract, the largest defense procurement program in the nation’s history.

Andrews said he will soon name the members of an expert advisory panel that will oversee the bidding process. He plans to visit Japan at the end of this week for a “goodwill trip” after traveling recently to Germany and France.