The Biden administration is concerned that a weakened Iran could build a nuclear weapon, White House National Security Adviser Jake Sullivan said on Sunday, adding that he was briefing President-elect Donald Trump's team on the risk, Reuters reported.

Iran has suffered setbacks to its regional influence after Israel's assaults on its allies, Palestinian Hamas and Lebanon's Hezbollah, followed by the fall of Iran-aligned Syrian President Bashar al-Assad.

Israeli strikes on Iranian facilities, including missile factories and air defenses, have reduced Tehran's conventional military capabilities, Sullivan told CNN.

"It's no wonder there are voices (in Iran) saying, 'Hey, maybe we need to go for a nuclear weapon right now ... Maybe we have to revisit our nuclear doctrine'," Sullivan said.

Iran says its nuclear program is peaceful, but it has expanded uranium enrichment since Trump, in his 2017-2021 presidential term, pulled out of a deal between Tehran and world powers that put restrictions on Iran's nuclear activity in exchange for sanctions relief, read the report.

Sullivan said that there was a risk that Iran might abandon its promise not to build nuclear weapons.

"It's a risk we are trying to be vigilant about now. It's a risk that I'm personally briefing the incoming team on," Sullivan said, adding that he had also consulted with U.S. ally Israel.

Trump, who takes office on Jan. 20, could return to his hardline Iran policy by stepping up sanctions on Iran's oil industry.

Sullivan said Trump would have an opportunity to pursue diplomacy with Tehran, given Iran's "weakened state."

"Maybe he can come around this time, with the situation Iran finds itself in, and actually deliver a nuclear deal that curbs Iran's nuclear ambitions for the long term," he said.

Saudi Arabia has resumed its diplomatic operations in Kabul, reopening its embassy on Sunday.

"Based on the desire of the government of the Kingdom of Saudi Arabia to provide all services to the brotherly Afghan people, it has been decided to resume the activities of the mission of the Kingdom in Kabul starting on December 22," the embassy posted on social media site X.

The Islamic Emirate of Afghanistan's acting foreign minister Amir Khan Muttaqi recently met with Saudi representatives, expressing a desire to expand bilateral relations. Saudi officials reaffirmed their commitment to providing humanitarian aid and strengthening collaboration in various fields.

In November 2021, Saudi Arabia said it was resuming consular services in Afghanistan. It also provides humanitarian aid in the country through its KSRelief organisation.

Saudi Arabia was one of only three countries, the others being Pakistan and the United Arab Emirates, that recognised the first IEA government which came to power in 1996 and was overthrown by the United States invasion of 2001.