"Tonight, I'm pleased to announce that we are taking our military cooperation to even greater heights by formally designating Saudi Arabia as a major non-NATO ally," Trump said, speaking at the White House dinner honoring Saudi Crown Prince Mohammed bin Salman. 

"I'm just telling you for the first time because I wanted to keep a little secret for tonight," the president added. 

The agreement is the latest overture between Washington and Riyadh during the crown prince's visit. Earlier on Tuesday, Trump and bin Salman announced Saudi Arabia would be investing $1 trillion into the U.S.

Additionally, administration officials said on Tuesday that an agreement to export semiconductor chips to Saudi Arabia could come as soon as this week. Trump also said he could see a nuclear civil cooperation deal between the two countries in the future.

However, the diplomatic overtures come as Trump has received criticism for rolling out the red carpet for bin Salman. The crown prince's visit to Washington is the first time he has been back in the U.S. capital since the murder of journalist Jamal Khashoggi in 2018. The CIA concluded that bin Salman likely ordered his killing. 

Saudi Arabia has also been the subject of fierce criticism over human rights issues and has faced questions over whether it played a role in the September 11, 2001, terror attacks on the U.S. 

Trump defended bin Salman in the face of questions on the topics from reporters on Tuesday, accusing a reporter from ABC News who asked about the topics that she was "embarrassing our guests." 

The crown prince jumped in, saying he feels "pain about the families of 9/11 in America."