US President George W Bush has begun a visit to Saudi Arabia, during which he is expected to encourage democratic reform and discuss relations with Iran.
King Abdullah and George W Bush are both friends and allies
Mr Bush, who is on a tour of the Middle East, was met by King Abdullah on his arrival in the Saudi capital, Riyadh.
He had flown in from the United Arab Emirates, where he warned that the danger posed by Iran should be confronted "before it's too late".
Mr Bush also made a forceful call for strengthening democracy in the region.
In his speech in Abu Dhabi on Sunday, he called the fight against extremism the great ideological struggle of our time, and said only freedom and justice would defeat it.
The BBC's Matthew Price, who is travelling with the president, says the Bush family has long been close to the Saudi royal family.
In Riyadh, Mr Bush will meet not just good allies, but good friends, our correspondent says.
He is expected to ask King Abdullah to support his recent efforts in the Middle East peace process and in particular to back Palestinian Authority President Mahmoud Abbas as he negotiates with the Israelis.
While visiting Israel and the Palestinian Territories on Thursday, Mr Bush said Israel had to end its occupation of some Arab land to enable the creation of a viable Palestinian state.
The president is also expected to ask the Saudi king to support his efforts to isolate Iran over its controversial nuclear programme.
In Abu Dhabi, he said Iran had defied the UN Security Council and destabilised the region by failing to be transparent about its nuclear programme.
Our correspondent says, however, that the Saudi government, like other states in the region, is unlikely to be able to offer him much on the Iranian issue.
Relations between the Gulf kingdom and Iran have been tense in the past, but in recent months there seems to have been a steady improvement, he says.
Mahmoud Ahmadinejad became the first Iranian president to perform the annual Hajj pilgrimage to Mecca last month.
Mr Bush's two-day visit to Saudi Arabia began as his French counterpart ended his.
President Nicolas Sarkozy told the king's consultative council: "France wants to be a friend of Saudi Arabia and the Arab world."
Mr Sarkozy also suggested discussing in the next few weeks the possibility of France helping Saudi Arabia develop a civilian nuclear programme.