Updated at 6:55 A.M. E.S.T.

The leaders of the world’s most powerful capitalist country and the world’s biggest Communist dictatorship will have their diplomatic knives out as they begin what is expected to be an hours-long parley in the unlikely setting of the idyllic isle of Bali, on the eastern end of Indonesia.

The diplomatic knife strokes will be subtle, not always even discernible, as Presidents Biden and Xi engage in measured, polite words that will scarcely conceal the fears and resentments they both harbor toward one another.

Mr. Biden, who’s spoken with Mr. Xi five times by phone, now wants to draw “red lines” — understandings that Mr. Xi may choose to get around, ignore, or simply oppose. Nothing personal, to be sure.

How, though, is Mr. Biden to deflect Mr. Xi’s insistence that the off-shore Chinese province of Taiwan really does belong to Communist China — and what’s sure to be his warning that Washington better stay away or else.

Or else what? Mr. Biden can reiterate, yet again, the doctrine of “strategic ambiguity” to cover the paradox of America’s “commitment” to both the defense of Taiwan and acceptance of the island as part and parcel of China.

So what will the Chinese do about that? Nothing beyond ever more words, is the conventional view, but then Mr. Xi will also want to press Mr. Biden on what, in practical terms, may count for more, namely increased tariffs imposed by the Trump administration.

These are compounded by new restraints on the sale to the Chinese of the advanced technology needed to produce more and better semiconductors. Chips turn out to be an issue in the Great Game of control over the western Pacific and the rest of Asia.

Taiwan and chips may rank at the top of the list, but this summit has more at stake. No longer are Americans and Chinese getting along fine, the Americans glad to be done with “Red China” under Mao, the Chinese lapping up the wonders of capitalism.

Now Maoism, if anything, is seeing a revival as the country’s most powerful leader since Mao not only tightens controls at home but expands Chinese influence everywhere. That concern was paramount in Mr. Biden’s remarks in Phnom Penh.

There he consorted with members of Asean, the Association of Southeast Asian Nations, and also held what was billed as a “trilateral summit” with Prime Minister Fumio Kishida of Japan and President Yoon Suk-yeol of South Korea.

Mr. Biden didn’t have to mention China or its president as he called for “freedom of navigation and overflight” in the East China Sea and the South China Sea, which China insists is part of its territory. He minced no words about China’s human rights abuses.

He mentioned specifically the repression of the Uighurs in the northern province of Xingjian. One major issue between the Americans and Chinese that Mr. Biden will want to stress, and Mr. Xi might prefer to ignore, is that of Ukraine.

China isn’t entering the war but is on Russia’s side — maybe not too strongly but enough to play into the summit. And then there’s North Korea. Would the Chinese please be so kind as to tell the North Korean dictator, Kim Jong-un, to stop firing missiles — and forgo any designs he may have for ordering a seventh nuclear test? 

Mr. Xi may say that China has its own problems with Mr. Kim and can’t easily tell him what to do, but China is the source of all North Korea’s fuel and much of its food.

Mr. Biden will skim over all these issues in a conversation that could break up rather quickly with steely smiles and cold handshakes — or go on for hours. None of the advance reports are saying for how long.

Mr. Biden and his top aides, the national security adviser, Jake Sullivan, and the secretary of state, Antony Blinken, will no doubt be fighting off jetlag in a time zone 13 hours ahead of Washington. The schedule says they will meet tonight, American time.

By Monday morning we might know more. These parleys may set the course of Sino-American relations — at least until another crisis like that when the Chinese staged war games all around Taiwan just to try to scare away the House speaker, Nancy Pelosi.