When Jensen Huang, Nvidia’s chief executive, joined the group of American business leaders traveling with President Trump to Beijing at the last minute this week, many took it as a sign that progress was in store for the company’s long-stalled sales in China.

But as the summit between Mr. Trump and Xi Jinping, China’s top leader, wrapped up on Friday, the fate of Nvidia’s artificial intelligence chips in China was no clearer than it had been before.

Even Jamieson Greer, the U.S. trade representative, seemed uncertain about Nvidia’s future in China, saying in an interview with Bloomberg News on Friday that it was up to Beijing whether Chinese companies would make more purchases from the American chip giant.

Last December, President Trump approved Nvidia, the world’s leading chip maker, to sell one of its most powerful A.I. chips, the H200, to China. But since then, the Chinese government has yet to greenlight any purchases, and no H200s have been sold.

Instead, Beijing has pushed Chinese companies to rely on homegrown technology from chipmakers such as Huawei.

Just before Mr. Trump met with Mr. Xi, China reached a milestone in its long-running quest for technological self-sufficiency. The Chinese start-up DeepSeek said for the first time that its latest artificial intelligence model had been optimized to run on Huawei chips.

Mr. Huang had long warned that this shift was coming. Soon, China’s A.I. companies will rely on Chinese hardware rather than American technology, eroding U.S. influence over A.I. development in China, he has predicted.

U.S. officials did not seem to push the issue during their trip to China this week.

The decision on whether to buy the H200 “is going to be a sovereign decision for China,” Mr. Greer said in the interview. “Obviously we think it could be helpful to them in the long run, but they’ll just have to make their decision on that.”

For years, Washington has used export controls to slow China’s progress in advanced technologies like A.I., and analysts had expected Chinese officials to air their frustration with those restrictions this week.

Despite Mr. Huang’s presence in Beijing, Mr. Greer said, the two sides had not discussed chip export controls at the meeting.

China was firmly committed to producing advanced chips at home and views the U.S. tech industry as a threat to that effort, he said.

“If we are ahead of the game, like we are on A.I. chips, sometimes they feel that can stop their own growth,” he said.

In Doha, the stranded gas tanker Rasheeda has become a dark joke.

For more than two months, the vessel has drifted in circles in the Persian Gulf near the Strait of Hormuz, carrying the liquefied natural gas that serves as the lifeblood of Qatar’s economy. Residents track the ship on maritime apps and ask one another: “Where is Rasheeda today?”

The looping tanker has become a symbol of the paralysis gripping global energy supplies — a crisis that has cost Qatar billions in lost revenue and helped create energy shortages worldwide.

Qatar, one of the world’s largest exporters of liquefied natural gas, has seen its industry hobbled since war erupted in the Middle East nearly 11 weeks ago and Iranian strikes damaged critical infrastructure. Even facilities that remain intact have shut down because fuel cannot move through the closed Strait of Hormuz.

Since the war began, ships have tried just about everything to get out of the gulf, from calling in high-level diplomatic favors to hand-stitching Pakistani flags, hoping ties to the country mediating the U.S.-Iranian negotiations might secure safe passage.

During a week in Qatar, I interviewed more than a dozen people with knowledge of Qatar’s L.N.G. operations. Sensitivity in Qatar about the scarring of the energy industry is high. So most of the people requested anonymity to speak openly about QatarEnergy — the powerful state-owned energy giant that is the backbone of the economy. The details and observations about the state of Qatar’s L.N.G. industry stem from these conversations.

The consensus from these discussions was that even if the strait reopened tomorrow, Qatari L.N.G. exports would remain crippled for months and most likely impaired for years.

The biggest obstacle is technical. Replacement parts for infrastructure damaged by Iranian attacks can take up to five years to procure. At the same time, global shipping companies no longer trust the route through the strait, potentially leaving much of Qatar’s remaining exports stranded.

QatarEnergy did not respond to requests for comment.

The damage to Qatari gas infrastructure was inflicted in March, when Iran launched a barrage of drones and missiles at Ras Laffan, the country’s L.N.G. production hub. Most were intercepted, but three of the 20 projectiles penetrated defenses and struck L.N.G. trains — the massive liquefaction units that supercool gas for transport.

Rashid Al-Mohanadi, a former engineer who worked on one of the damaged units, remembered the night of the attack. Looking north from his home outside Doha, he saw the sky over Ras Laffan flash with interceptor missiles. The explosions rolled outward like shock waves, rattling the windows and doors of his house. When he stepped outside, the horizon was thick with black smoke.

“That was the moment I realized something had gotten through,” he said.

The facility was already largely idle because Iran had shut the Strait of Hormuz weeks earlier. Experts say the timing most likely spared the plant from further damage, as the lines were not operating under full pressure. Even so, Iran appeared to have hit what engineers describe as the “heart” of L.N.G. liquefaction trains.

The two heavily damaged units accounted for about 17 percent of Ras Laffan’s production. QatarEnergy has indicated that restoring full capacity could take three to five years. Some analysts believe that the estimate is high, but most agree that the recovery will take years.

The strikes appeared to have damaged the main cryogenic heat exchangers, precision machines that perform the final cooling of the gas and whose manufacturing is dominated by a single U.S. company, a unit of the conglomerate Honeywell. Replacement units can take four to five years to obtain.

The heat exchangers are a relatively small target within the Ras Laffan complex, which is more than twice the size of San Francisco, suggesting the strike was aimed at inflicting lasting damage.

Even for infrastructure that survived, getting fuel to market will remain difficult. Unlike the United Arab Emirates and Oman, which have coastlines on the Arabian Sea or Gulf of Oman, Qatar is uniquely vulnerable. All of its maritime infrastructure sits deep inside the Persian Gulf, leaving it without an alternative route to open water.

Roughly 1,600 vessels remain trapped near the Strait of Hormuz, carrying L.N.G., oil and fuel byproducts. After reports that Iran was allowing Pakistani-flagged vessels through, some crews stitched together makeshift flags from scraps of cloth found on board. It did not work.

For shippers, the danger will persist even if a cease-fire holds. Tehran has claimed to have seeded the waterway with undersea explosives. Until international mine-clearing units or Iranian authorities provide credible guarantees of safety, shipping companies are likely to be reluctant to risk their crews’ lives.

The Philippines, which supplies much of the world’s merchant-mariner work force, has begun directing crewing agencies to stop sending Filipino sailors into the conflict zone. Fears of further Iranian aggression and a lack of insurance coverage for such voyages threaten to keep vessels away. That leaves QatarEnergy in a bind.

Qatar cannot simply restart production until it secures commitments from shipping lines to return for new cargoes. If gas continues to accumulate with nowhere to go, storage tanks could overflow, forcing shutdowns that risk permanent damage. Because of that bottleneck, the entire export system is unlikely to return to normal for at least three to four months after the strait reopens.

The full extent of the damage is still unclear, but given the scale of the repairs required, “we’re talking reduced production until the end of the decade,” said Henning Gloystein, a managing director for energy at Eurasia Group, a political risk research firm. “It’s a significant tightening of the market.”

Even if the immediate crisis is resolved, many in the energy industry think that the Strait of Hormuz will not return to what it was. Support is growing for enormous infrastructure projects designed to bypass the strait, potentially redrawing the Middle East’s energy map.

One frequently discussed proposal is a pipeline across the Arabian Peninsula to a new liquefaction and export terminal in Jeddah on the Red Sea. Another would extend pipelines south to the Omani port of Duqm, allowing Qatari gas to be loaded directly onto ships in the Arabian Sea.

But pipelines carry geopolitical risks of their own. Relations between Qatar and Saudi Arabia — through which any overland route would have to pass — are warm now but scarred by a yearslong rift in which the kingdom cut off diplomatic and transport ties. Pipeline infrastructure is also vulnerable to missile and drone attacks.

For now, the immediate urgency is reopening the waterway itself. “Priority No. 1 is getting the strait open,” said Mr. Al-Mohanadi, the engineer who used to work at Ras Laffan. “Then it becomes about finding a mechanism to keep it open.”

After nearly a decade at a QatarEnergy-Exxon Mobil joint venture, Mr. Al-Mohanadi joined the Doha-based Center for International Policy Research as a vice president. He said one option was to create a multilateral maritime insurance “piggy bank” — a private and sovereign-backed fund that would insure ships transiting dangerous waterways such as the strait.

He also said there was growing pressure for Asia’s largest energy consumers to take a more active role in regional maritime security. For decades, the United States has served as the Gulf’s de facto guarantor, maintaining military bases across the region. Mr. Al-Mohanadi argues that the burden should increasingly be shared by Asian “middle powers” most dependent on Middle Eastern energy exports.

“We’re in a period of history where it’s a jungle, and that is threatening global energy security and entire economies,” he said recently over a late-night coffee at a hotel overlooking the waters off the northern tip of Doha Bay.

Near the end of our conversation, Mr. Al-Mohanadi opened a maritime tracking app on his phone. He typed in “Rasheeda,” and out emerged a rendering of the tanker, still endlessly circling the gulf. “Poor Rasheeda,” he said, looking down at the screen. “At this point, she must be so tired.”