US Secretary of State John Kerry has landed in Saudi Arabia, the second stop on his tour of the Middle East.
America’s top diplomat is expected to try to repair ties with a long-standing ally that have been frayed by the conflict in Syria and the recent US outreach to Iran.
He first made an unscheduled stop in Egypt, where he called for an end to violence and a move to full democracy.
Mr Kerry also said the US is committed to working with Egypt’s new rulers.
Egypt is one of the issues that has caused tension between Saudi Arabia and the United States in recent months.
Washington froze some of the $1.3bn (£810m) it gives in aid annually to Egypt when the democratically elected president Mohammed Morsi was ousted by the army earlier this year, while Saudi Arabia has thrown its support behind the new military-backed government.
It had earlier been widely reported that the Saudi intelligence chief, Prince Bandar bin Sultan, had told European diplomats his country would be making “a major shift” in its relations with the US.
Secretary Kerry is expected to try to smooth over tension regarding Egypt and other issues, including US reluctance to act on Syria, with the Saudi leadership.
Saudi Arabia is reportedly unhappy that peace talks over Syria could lead to an Iran-backed government in Damascus.
Riyadh is also concerned about a US-Iran rapprochement over Tehran’s nuclear programme.
Saudi Arabia is an important diplomatic and trading partner for the US.
Speaking in Cairo before he flew to to Riyadh, he said he would not allow countries like Saudi Arabia, Jordan and Egypt to be “attacked from the outside” – a message which was viewed by some as a veiled reference to Iran.
He also stressed the need for Egypt to move toward democracy.
“History has demonstrated that democracies are more stable, viable and prosperous than any alternative,” he told a news conference.
“With stability comes tourism and investment, and with both come jobs.”
The BBC’s Kim Ghattas, travelling with Mr Kerry, says it is the kind of precaution that characterises trips by US officials to countries like Afghanistan and Iraq.
This is a sign of US concerns about continued instability in the country, but it is also a reaction to the high level of anti-American feeling in Egypt, our correspondent says.
Mr Kerry said Egypt’s fortunes, and its bilateral relations, depended on its democratic transition.
He said that the US was “committed to work with” the interim government.
Mr Kerry’s nine-day trip will take in a number of countries in the region and in Europe, including the United Arab Emirates, Algeria, Morocco, Jordan and Poland.
The secretary of state will also meet Israeli and Palestinian leaders to discuss the peace process in Jerusalem and Bethlehem.
Correspondents say Mr Kerry may have to face difficult questions over allegations of widespread US spying.