US President Joe Biden and Chinese leader Xi Jinping agreed on joint efforts to combat fentanyl, restore high-level military communications and hold a dialogue about artificial intelligence at a high-stakes summit that saw the two leaders seek to repair a bilateral relationship under intense strains.

The discussion also included a extended discussion of foreign policy, with Xi denying reports that China was readying plans for a mass invasion there, according to US officials. Biden responded that the US believed in the status quo, and asked the Chinese to respect the electoral process in the upcoming elections. The US leader also said China should rethink accelerated military drills in the region.

US officials also pressed their Chinese counterparts to discuss the conflict between Israel and Hamas with Iran, which financially supports the militant group categorized as a terrorist organization by the US and EU.

Biden and Xi met Wednesday on the sweeping grounds of the Filoli estate in the town of Woodside, about 25 miles south of San Francisco. The meeting, which lasted over four hours, also saw an agreement to work to increase flights between the two countries next year, according to Xinhua news agency.

In a message on X, formerly known as Twitter, Biden said the talks were “some of the most constructive and productive discussions we’ve had.”

The carefully choreographed meeting went multiple sessions - including a working lunch featuring herb ricotta ravioli, heritage chicken, and almond meringue cake - with the pair and their top aides huddling in a secluded century-old Georgian manor south of San Francisco.

The leaders of the world’s two largest economies had not spoken for a year, a stretch which saw the US-China relationship reel from a series of diplomatic and military missteps and intensifying economic competition.

The deal from China on combating fentanyl was characterized by senior US officials as the most important agreement from the summit — and said Biden told Xi that it posed one of the worst drug problems the US had faced. The officials, who spoke on condition of anonymity, said they would watch closely to see if China follows through on the pledge.

More than 150 people in the US die each day from overdoses related to synthetic opioids, according to the Centers for Disease Control and Prevention. And the issue has become a political flashpoint with Republican presidential candidates vowing to use military force against drug cartels in Mexico and disrupt economic ties between the US and China unless Beijing moved on the issue.

The move to recharge senior military-to-military communications was also high on the agenda following a series of close encounters between Chinese and American ships and planes in recent months.

China agreed to policy level discussions with US Defense Secretary Lloyd Austin and his Chinese counterpart, as well as operational engagements at senior military levels, according to the US officials. That restores communications channels that China halted between the two countries last year in protest of then-House Speaker Nancy Pelosi’s visit to Taiwan.

Since then, US officials have pushed hard to resume the talks. US Secretary of State Antony Blinken detailed a recent Chinese jet’s intercept of a US B-52 in international airspace over the South China Sea during Foreign Minister Wang Yi’s recent visit to Washington, according to a person familiar with the discussion.

Blinken noted the table he and Wang were sitting at was 10 feet — the same space between the two aircraft during the incident — to highlight the need to restore communications to prevent conflict, according to the person, who spoke on the condition of anonymity.

On artificial intelligence, the two sides agreed to a dialogue to keep the emerging technology from being deployed in ways that could destabilize global security, according to the US officials.

Biden has made regulating AI a focus of his administration, signing an executive order last month that tasks federal agencies with setting standards for safety and security and requires developers to safety-test new models before releasing them to the public.

Not all of the conversation was serious. Biden and Xi, who have known each other for years and used to meet when both served as their countries’ respective vice presidents, traded memories of previous interactions. At one point, Xi jokingly thanked Biden - who is celebrating his birthday next week - for reminding him that his wife’s celebration was also coming up.

Ahead of the Biden-Xi meeting, the US and China released a statement detailing new commitments to cooperate on climate change, with promises to build carbon-capture facilities, curtail power sector pollution and take aim at the full suite of greenhouse gases helping warm the planet.

The statement from the world’s top two greenhouse gas emitters is seen injecting new momentum ahead of the crucial COP28 summit that starts in Dubai this month, boosting the odds of successful negotiations, while underscoring their shared alarm about climate change.

Tackling global warming is one of the rare areas of consensus between Beijing and Washington.

Biden asked Xi to do more on climate including taking steps on limiting methane emissions in the short term, the US officials said.

--With assistance from Shawn Donnan, Jennifer A. Dlouhy, Akayla Gardner and Jenny Leonard.

(Updates with additional details throughout)