In reply to the government’s paper, Mr. White said Australia’s stance was unrealistic because it clung too much to the vestiges of a fading power that would not be able to stay ahead of China’s economic strength.

“The paper has an elegiac feel, the sense of a sunset,” he said in an interview.

The biggest splash came from Mr. White’s recommendations for what Australia should do about an American retreat. Faced with what he called Chinese efforts to impose its influence and different political values, he said Australia will have to do more to defend itself, including perhaps even one day acquiring nuclear weapons.

He said China’s rise is likely to spark an arms race in the Asia-Pacific, with both Japan and South Korea likely to become nuclear powers within a couple of decades.

“And the logic that drives them has implications for others,” Mr. White said. Australia could remain a middle power, he said, by keeping only a small nuclear arsenal. “It might look something like Britain’s submarine-based nuclear force,” he wrote.

American officials have tried to counter such conclusions. During his visit to Sydney in April, Vice President Mike Pence told Australian business and government leaders that the United States remains Australia’s most vital economic partner, with American investment growing by 50 percent in the past three years.

Another sign that Washington may seek to reassure its Australian allies has been talk of the possible appointment of Adm. Harry B. Harris Jr., the United States commander in the Pacific, as the next ambassador to Australia. Some American officials have said they would welcome the move because it would send a message to China that the United States will not retreat.