US President Donald Trump and Saudi Crown Prince Mohammed bin Salman have discussed military deals, investment in the US, and security cooperation, during the prince's first visit to the White House.

On On Tuesday, bin Salman sat down with US President Donald Trump at the Oval Office and discussed an agreement last year for $200 billion worth of Saudi investments in the US, including large purchases of US arms. 

Trump held up charts to show the depth of Saudi purchases of US military hardware, ranging from ships to missile defence to planes and fighting vehicles.

"Saudi Arabia is a very wealthy nation, and they're going to give the United States some of that wealth, hopefully in the form of jobs, in the form of the purchase of the finest military equipment anywhere in the world," he said.

Trump also praised the “great friendship” with Saudi Arabia and its crown prince.

“The relationship is probably the strongest it's ever been -- we understand each other,” said the US president. “We really have a great friendship, a great relationship.”

The heir to the Saudi throne arrived in Washington on Monday as part of his three-week multi-city tour of the United States.

Meanwhile, US Senate has voted against a resolution seeking to end American support for Saudi Arabia’s military campaign against Yemen.

The upper chamber of Congress voted 55 to 44 on Tuesday against the measure introduce by anti-war senators.

The resolution would have forced US President Donald Trump “to remove United States Armed Forces from hostilities in or affecting the Republic of Yemen,” except operations against al-Qaeda or affiliated forces.

Washington, along with the UK, has been the main arms provider to Saudi Arabia during the military campaign, which has killed over 13,600 people in Yemen as it is about to enter its third year on March 25.