The United States wants to see a strong Saudi Arabia, Defence Secretary Jim Mattis said during talks Wednesday aimed at reinvigorating the Riyadh-Washington alliance.
Mattis, meeting top officials in the Saudi capital, also hinted that President Donald Trump could visit the kingdom, a longtime US ally which has welcomed Washington's firmer line against common adversary Iran.
"It is in our interest to see a strong Saudi Arabia," Mattis said at the start of talks with Deputy Crown Prince Mohammed bin Salman, the defence minister, pointing to the country's "military security services and secret services."
"What we can do here today could actually open the door possibly to bringing our president to Saudi Arabia," Mattis said.
Mattis, a retired four-star Marine general, earlier met King Salman at Al-Yamama Palace in Riyadh, where he told the monarch: "It's good to be back."
Mattis commanded troops during the 2003 invasion of Iraq.
He arrived in the kingdom on Tuesday afternoon to listen to Saudi leaders and learn "what are their priorities," an American defence official said earlier.
The United States and Saudi Arabia have a decades-old relationship based on the exchange of American security for Saudi oil.
But ties between Riyadh and Washington became increasingly frayed during the administration of president Barack Obama.
Saudi leaders felt Obama was reluctant to get involved in the civil war in Syria and was tilting toward Riyadh's regional rival Iran.
The Sunni Muslim kingdom "felt marginalised" during international negotiations on a nuclear accord with Shiite Iran, the defence official said.
That deal, signed in July 2015 by the Obama administration, saw the lifting of international sanctions in exchange for guarantees that Tehran would not pursue a nuclear weapons capability.
- New Iran sanctions -
Saudi leaders worry about Iran interfering in Arab countries by using local Shiite communities, as in Bahrain, Lebanon and Yemen.
Bordering Saudi Arabia, Yemen has been torn for more than two years by a civil war between Iran-backed Huthi rebels, their allies, and pro-government forces aided by a Saudi-led military coalition that receives some military support from the US.
The Saudis have found a more favourable ear in Washington under Trump, who has denounced Iran's "harmful influence" in the Middle East.
In February, Trump imposed new sanctions on Tehran after a ballistic missile test launch, and in response to its support for Yemen's rebels.
Prince Mohammed told Mattis that Saudi Arabia and the United States are working to counter challenges in the region, including "the malign activities of Iran" and to bring stability "to the most important straits."
The US military is watching Huthi activities along the strategic Bab al-Mandab strait connecting the Red Sea with the Indian Ocean.
Yemeni rebels in late January attacked a Saudi warship in the Red Sea, and they are also believed to have fired missiles towards US warships in the area.
The United States accuses the rebels of deploying coastal defence missiles and other weapons which threaten free navigation in the waters which are vital to global trade.
- Anti-IS campaign -
Trump's Yemen focus has so far been on a major escalation of attacks against jihadists from Yemen-based Al-Qaeda in the Arabian Peninsula.
Pentagon officials have so far remained cautious on what they might do to support Saudi Arabia.
The Trump administration could, for example, lift a freeze on the delivery of precision guided bombs to the kingdom.
Obama's government blocked their transfer in December because of concerns over civilian casualties in Yemen.
Washington would also like Riyadh to step up its participation in the campaign against the Islamic State group in Iraq and Syria.
Options include the kingdom intensifying its aerial operations or its humanitarian aid, the American defence official said, describing the fight against IS as "our number one concern".
Mattis was expected to raise with the Saudis Washington's intentions towards Syria, where Riyadh has aided some rebel groups.
Earlier this month, the US fired cruise missiles against a Syrian government airbase after a suspected chemical bombing of a rebel-held town which Washington blamed on President Bashar al-Assad.
After Saudi Arabia, Mattis travels Thursday to Egypt and then to Israel on Friday before returning to the Gulf Saturday for talks in Qatar.