The weapons "will support U.S. foreign policy and national security objectives by improving the security of a friendly country," the State Department said.
The State Department on Thursday announced the sale of 6,700 anti-tank missiles to Saudi Arabia, hours after Crown Prince Mohammed bin Salman met Defense Secretary Jim Mattis to discuss the Saudi-led bombing of Yemen.
The State Department said it had notified Congress of the proposed sale, part of a $1 billion defense deal that also includes parts and maintenance support for Saudi tanks and helicopters.
The main contractor for the missiles is Tucson, Arizona-based Raytheon.
"This proposed sale will support U.S. foreign policy and national security objectives by improving the security of a friendly country which has been, and continues to be, an important force for political stability and economic growth in the Middle East," the State Department said, adding that the deal "will not alter the basic military balance in the region."
The deal comes almost three years to the day that Saudi Arabia, supported by the U.S., began a campaign of airstrikes against Houthi rebels in Yemen.
Rights group Amnesty International said Friday that arms deals were "irresponsible" because all parties to the conflict had "repeatedly violated international law."
"There is extensive evidence that irresponsible arms flows to the Saudi Arabia-led coalition have resulted in enormous harm to Yemeni civilians," it said in a statement, "But this has not deterred the USA, the U.K. and other states, including France, Spain and Italy, from continuing transfers of billions of dollars' worth of such arms. As well as devastating civilian lives, this makes a mockery of the global Arms Trade Treaty."
The Senate on Tuesday voted to defeat a war powers resolution for Yemen that represented an attempt to insert congressional oversight into U.S. military operations in the deadly civil war there. The measure, which called for the end of the U.S. role in the war, was co-sponsored by three members representing the full ideological spectrum of the Senate — Sens. Bernie Sanders, I-Vt., Mike Lee, R-Utah, and Chris Murphy, D-Conn. The Senate voted to block the resolution by a vote of 55-44.
Thursday's deal came two days after bin Salman met President Donald Trump, and hours after he held talks with Pentagon leaders including Mattis.
Asked if he would raised concerns about civilian casualties in Yemen during his meeting, Mattis told reporters: "We have been working very hard with the new U.N. envoy to end the fight in Yemen. And we believe that Saudi Arabia is part of the solution. They have stood by the United Nations recognized government. And we are going to end this war. That's the bottom line."
Under the proposed defense deal, Saudi Arabia will buy: 6,696 TOW 2B missiles and associated training materials worth $670 million; parts and repairs support worth $300 million for its Abrams tanks and fighting vehicles, and maintenance equipment worth $100 million for its fleet of AH-64D/E, UH-60L, Schweizer 333 and Bell 406CS helicopters.
The U.S. military drastically stepped up its air campaign in Yemen last year, conducting more than six times as many airstrikes as in 2016, according to data from U.S. Central Command (CENTCOM).