RIYADH, Saudi Arabia — President Trump will begin an ambitious five-city, nine-day foreign trip in Saudi Arabia on Saturday with the goal of uniting the Muslim world against terror — even as his presidency is embroiled in a quickly escalating controversy over his ties to the Russian government.

Presidents often turn to foreign affairs when there’s trouble at home, but President Trump’s very first foreign trip comes amid a succession of breathtaking developments over his firing of the FBI director, contacts with Russian diplomats and the appointment of special counsel to investigate.

As the bombshells multiply in Washington, Trump himself appears eager for a change in subject. Asked about the Russia investigation at a press conference Thursday, Trump brought up the foreign trip.

“Tomorrow, as you know, I’m going to Saudi Arabia, going to Israel. I’m going to Rome. And we have the G7. We have a lot of great things going on,” he said. “So I hate to see anything that divides. I’m fine with whatever people want to do, but we have to get back to running this country really, really well.”

Still, the headlines put even more pressure on the White House to deliver a foreign policy victory, but White House officials seemed to be tamping down expectations this week. And experts said domestic issues can’t help but to be a distraction.

“His current domestic political problems are a deepening concern,” said Jim Phillips, a senior fellow at the Heritage Foundation who’s been supportive of Trump’s Middle East policy. “I think President Trump’s standing at home definitely will be a factor in the perceptions of friends and allies abroad, and in how they interact with him.”

But in Riyadh, there’s a clear sense of national pride that Trump chose Saudi Arabia as his first foreign destination as president. Bright…