Some have accused the Saudis of war crimes in Yemen. More than 10,000 people have been killed in the civil war in Yemen, according to the United Nations.
In a Huffington Post op-ed Saturday, Murphy called the Saudi arms deal "a terrible idea." He noted that the Obama administration wouldn't sell "precision-guided munitions because the Saudis were using U.S.-provided munitions to repeatedly target civilians and humanitarian sites in their bombing campaign inside Yemen."
The Saudi deal includes various munitions supplied by Raytheon as well as air defense system technology from the defense contractor.
"There was a lot of reluctance on behalf of the previous administration to allow the Saudis to buy a lot of equipment," said Jeff Sorenson, a former U.S. Army chief information officer and now partner at A.T. Kearney in Washington, where he leads the public sector practice.
Sorenson said the arms deal sends a strong message to Iran, pointing to the recent comments from Trump.
In remarks Monday during his visit to Riyadh, Trump blasted Iran as "a regime that is responsible for so much instability in the region." The president also hailed the landmark arms sale, saying it will help the Saudis "take a greater role in security operations."
"The most interesting feature of this [arms] transaction is that the Saudis will begin to produce weapons for themselves," said Loren Thompson, COO of the nonprofit Lexington Institute, a defense think-tank based in Arlington, Virginia.
Under the deal, Lockheed Martin is teaming with a Saudi firm to assemble about 150 Black Hawk helicopters. The Saudis also will manufacture other defense technology as part of the kingdom's diversification strategy. It comes as Iran also is manufacturing more of its own weapons.
The Saudi defense package also includes air and missile defense systems from Lockheed as well as combat ships and other military technology.
Additionally, Boeing is selling the Saudis guided weapons systems in the defense package as well as aircraft.
Watch: Saudis welcome Trump with billions in corporate deals