Barack Obama holds talks with Saudi Arabia's King Salman
US President Barack Obama and King Salman of Saudi Arabia have held talks in Riyadh ahead of a regional summit.
Correspondents say the leaders appear to have disagreed on issues including Iran, Syria, Yemen and the fight against so-called Islamic State militants.
President Obama also challenged the king on the issue of human rights.
The White House said the leaders had affirmed their "historic friendship and deep strategic partnership".
Mr Obama is on a two-day visit to Saudi Arabia, which is likely to be his last as president.
He will meet the leaders of Kuwait, Qatar, Bahrain, the United Arab Emirates and Oman at a summit of the Gulf Co-operation Council on Thursday, before travelling to the UK and then Germany.
Press plays down 'farewell summit'
While Saudi press hails strong relations with the US, Middle Eastern newspapers in general are playing down Barack Obama's visit, arguing that he does not have enough time before leaving office to mend strained ties, BBC Monitoring reports.
Saudi-owned Al-Hayat sees the visit as "a farewell summit" for the US president: "Obama will no longer be either useful or relevant to the Gulf states," it says.
Pan-Arab Al-Arab al-Alamiyah agrees, saying that key issues are "most likely to be passed over to the next US administration, which may be better placed to deal with them".
Rajeh al-Khoury in Lebanese Al-Nahar says Mr Obama will not be able "to correct his illusions about Iran, but will rather leave behind a lesson about failure".
Saudi pro-government Al-Riyadh urges the US and Saudi Arabia to "square up to growing mutual challenges that include rebuilding confidence".
Rim al-Harami in Qatari Al-Raya concurs, saying "the challenges remain but they could be overcome if confidence is regained".
US support for the lifting of sanctions against Iran has damaged relations with Saudi Arabia, Iran's biggest rival in the region.
And a bill that is being considered in the US at the moment could potentially allow American citizens to sue Saudi Arabia over the 9/11 attacks.