U.S. President Donald Trump standing next to Mohammed bin Salman, Crown Prince of Saudi Arabia, during a group picture at the start of the Group of 20 summit on 28 June 2019.

President Donald Trump said on Saturday he appreciated Saudi Arabia's purchase of U.S. military equipment, calling Crown Prince Mohammed bin Salman a "friend of mine" who had worked to open up the country with economic and social reforms.

Trump's plan to boost defense sales to the kingdom has hit obstacles in Congress, where Democrats and some fellow Republicans are not happy about human rights abuses, including the murder last year of Saudi journalist Jamal Khashoggi.

"It's an honor to be with the crown prince of Saudi Arabia, a friend of mine — a man who has really done things in the last five years in terms of opening up Saudi Arabia," Trump said ahead of a bilateral meeting with the crown prince, known as MBS, in Osaka, Japan.

"I think especially what you've done for women and seeing what's happening — it's like a revolution in a very positive way," he added on the sidelines of the Group of 20 (G20) summit.

"We're trying to do our best for our country, Saudi Arabia, and it's a long journey," the crown prince said.

The Senate this month voted to block the sale of billions of dollars of military equipment to Saudi Arabia, the United Arab Emirates and other countries, rejecting Trump's decision to sidestep Congress's review of such deals by declaring an emergency over Iran.

Trump has promised to veto the Senate action.