WASHINGTON A $110 billion arms deal with Saudi Arabia that President Donald Trump announced Saturday would be illegal because of the Saudis role in the ongoing conflict in Yemen, according to a legal analysis the Senate received Friday.

The U.S. cannot continue to rely on Saudi assurances that it will comply with international law and agreements concerning the use of U.S.-origin equipment, Michael Newton, a prominent Vanderbilt University law professor and former military judge advocate general, said in an opinion sent to the full Senate by the human rights arm of the American Bar Association. He cited multiple credible reports of recurring and highly questionable [air]strikes by the Saudi military that have killed civilians.

In a 23-page assessment, Newton said the strikes have continued even after Saudi units received training and equipment to reduce civilian casualties.

Continued sale of arms to Saudi Arabia and specifically of arms used in airstrikes should not be presumed to be permissible under the two statutes covering most sales of military equipment by the U.S government to foreign nations, he said.

The State Department said Saturday in a statement that the sales would occur under the foreign military sales process. Newton told senators that should not be available to Saudi Arabia until the Saudi and U.S. governments offer new certifications to prove that the Saudis are following the law on using U.S. weaponry. The arms package includes tanks, artillery, ships, helicopters, missile defense systems and cybersecurity technology worth almost $110 billion, according to the statement .

The Obama administration committed to many elements of the package, but the Trump administration is presenting it as a major accomplishment. Jared Kushner , Trumps son-in-law and a White House aide, has built a rapport with Saudi Deputy Crown Prince Mohammed bin Salman and personally intervened with weapons manufacturer Lockheed Martin to get the Saudis a better deal, The New York Times reported .

The bar associations Center for Human Rights requested the assessment after receiving several congressional inquiries about the legality of continued sales to the Saudis. Senators skeptical of the Saudi campaign in Yemen unsuccessfully tried to block a $1.15 billion arms transfer last fall . The legal analysis suggests that they should try again.

Theres already an apparent appetite for such a move: Sen. Chris Murphy (D-Conn.), an architect of last years effort, blasted the deal in a HuffPost blog post on Saturday. Saudi Arabia is an important friend and partner for the United States, Murphy wrote. But they are still a deeply imperfect friend. $110 billion in weapons will exacerbate, not ameliorate, those imperfections.

A U.S.-backed, Saudi-led coalition of countries has been at war in Yemen for over two years, fighting Iran-backed militants who have taken over much of the country. The coalition has been repeatedly accused of war-crime violations for its role in the deaths of thousands of civilians in the Arab worlds poorest country.

The United Nations has reported nearly 5,000 deaths have occurred, and said the actual toll is likely far higher. U.N. experts have repeatedly singled out coalition airstrikes, which are supported by American aerial refueling, as the single largest cause of civilian casualties during various periods in the conflict. Meanwhile, naval blockades by the coalition and interference in aid deliveries by the pro-Iran militants have caused a major humanitarian crisis: 19 million Yemenis are in need of aid, according to the U.N., and a famine may soon be declared.

Extremist groups, notably al Qaeda, have taken advantage of the chaos to expand their power.

Then-President Barack Obama authorized U.S. assistance to the coalition in March 2015. His administration halted some arms transfers last December after a major Saudi-led attack on a funeral , but it kept up the majority of U.S. support.

Obama approved a record-breaking $115 billion in arms sales to the Saudis during his time in office, but the countrys leaders frequently claimed he abandoned them because of his nuclear diplomacy with Iran and reluctance to strongly intervene in Syria. Trumps team is speaking of the deal as a sign of a renewed commitment to the longtime U.S. partner even though he often criticized the Saudis on the campaign trail.

Newton, in his analysis, charged that Saudi military strikes have deliberately targeted markets and hospitals where few, if any, enemy combatants were located. He also cited Saudi Arabias domestic human rights abuses, its failure to hold military officers accountable and its illegal use of cluster munitions as justifying an immediate end of U.S. military support.

U.S. personnel or contractors could be vulnerable under international humanitarian law if the military sales continue, Newton added especially because the armaments could be used in an anticipated Saudi assault on the Yemani port of Hodeidah, which would have a devastating impact on millions. One-time military lawyer Rep. Ted Lieu (D-Calif.) has suggested that such prosecution is possible.

Despite failed private efforts to improve the humanitarian situation in Yemen, the Trump administration has not expressed much public concern about the Saudis conduct in the conflict. Its instead loudly cheered the kingdom and chosen it as the site for Trumps first foreign visit, which the Saudis are promoting as an epoch-defining moment.

This package demonstrates the United States commitment to our partnership with Saudi Arabia, while also expanding opportunities for American companies in the region, potentially supporting tens of thousands of new jobs in the United States, the State Department said Saturday in its release.

The statement did not mention the U.S. and Saudi role in the controversial Yemen war.

Speaking Saturday in the Saudi capital, Secretary of State Rex Tillerson said continued U.S. arms transfers were meant to help Saudi actions in Yemen.

The Saudi side suggested total coherence on the issue, despite the war crimes allegations and lawmakers vocal complaints.

There are many who try to find gaps between the policy of the United States and that of Saudi Arabia, but they will never succeed, Saudi foreign minister Adel al-Jubeir said in a statement issued Friday by the Saudi Embassy in Washington. The position of President Trump, and that of Congress, is completely aligned with that of Saudi Arabia. We agree on Iraq, Iran, Syria and Yemen. Our relationship is on an upward trajectory.

Read the full legal analysis on future U.S. arms sales to Saudi Arabia below:

This article has been updated to reflect that Trump has announced the deal and to include more reactions to it.

CORRECTION: The Associated Press did not report that the arms package includes planes and bombs, as an earlier version of this story said.