A senior member of the Saudi royal family has warned against a US troop withdrawal from Syria.
Prince Turki al-Faisal told the BBC the action would have a negative impact, further entrenching Iran, Russia and the rule of President Bashar al-Assad.
US President Donald Trump announced in December that it was time to bring US troops home from Syria.
Prince Turki was speaking just before US Secretary of State Mike Pompeo began a visit to Riyadh.
Mr Pompeo is on a tour of the Middle East, and has already visited Iraq, Jordan, Egypt and Bahrain.
What did Prince Faisal say?
He said that the world community was guilty of neglecting the Syrian people and the US troop withdrawal would make things worse.
"The US actions from my perspective is that it is going to further complicate, rather find any solutions to it and further entrench not only the Iranians, but also the Russians and Bashar al Assad, so from the perspective it is a very negative development," he said.
The prince added that the departure of Defence Secretary James Mattis in December was unlikely to help matters either.
"Obviously he disagreed with the administration on Syria policy so in that context his remaining would have been a more positive sign of commitment to that policy," he said.
The prince is no longer a member of the Saudi government, but has decades of experience within it.
BBC State Department correspondent Barbara Plett says that while he is most likely reflecting Saudi official opinion he is not speaking for the government.
What is Mike Pompeo going to talk about?
US media report that he is expected to discuss Iran and the conflicts in Yemen and Syria during his time in Riyadh, as well as seeking an update on the investigation into the murder of journalist Jamal Khashoggi.
He said at a news conference in Qatar that he would ask Crown Prince Mohammed bin Salman to hold Khashoggi's killers "accountable".
The trip to Riyadh comes just three months after the murder of Khashoggi, a critic of Saudi's rulers, at the Saudi consulate in Istanbul.
Riyadh has admitted he was murdered there, but denied suggestions that the crown prince was involved. It had initially maintained that the writer left the consulate unharmed.
"We will continue to have a conversation with the crown prince and the Saudis about ensuring accountability," Mr Pompeo said at a news conference in Qatar on Sunday.
What else has Pompeo discussed on his trip?
Speaking in Qatar, America's most senior diplomat also called for more unity between Arab states, urging an end to the 18-month economic boycott of Qatar.
Saudi Arabia, the UAE, Bahrain and Egypt - all US allies - cut ties with Qatar in June 2017, accusing the oil-rich state of supporting the region's terrorist groups and Iran - Saudi Arabia's main regional rival.
Qatar denies that, and has accused its neighbours of seeking regime change.
Mr Pompeo's trip is intended to reassure America's Middle East allies of its commitment to the region.
On 15 January the US secretary of state will visit Kuwait, where he is expected to sign an agreement to "boost the strategic dialogue between the two countries", according to Kuwait's state news agency.