WASHINGTON — A controversial arms deal for Arab allies approved by the Trump administration will allow U.S. hi-tech bomb parts to be manufactured in Saudi Arabia, giving Riyadh unprecedented access to a sensitive weapons technology.

The production arrangement is part of a larger $8.1 billion arms package for Saudi Arabia, the United Arab Emirates and Jordan announced two weeks ago. The Trump administration pressed ahead with the sale without congressional approval, declaring an "emergency" based on what it said was a heightened threat from Iran.

The deal came as a surprise to lawmakers, who were outraged that the administration chose to bypass Congress. But most members of Congress only learned days after the deal was announced May 24 that it opens the door for Saudi Arabia to host the production of electronic guidance and control systems for Paveway precision-guided bombs, congressional aides said.

The New York Times first reported on the co-production arrangement.

Lawmakers are expected to grill a senior State Department official — R. Clarke Cooper, assistant secretary of state for political-military affairs — about the arms deal and the bomb production plan at a House Foreign Affairs Committee hearing Wednesday.

The U.S. government tends to closely guard technology linked to sophisticated weapons, and limits how much of that technology is shared through co-production projects with other countries.

Lawmakers opposed to the deal said the production scheme sent the wrong signal to Saudi Arabia given its human rights record and its air war in Yemen, raised security concerns about sharing so-called "smart bomb" technology with Riyadh and undercut one of President Donald Trump's arguments for selling weapons to the Saudis — to generate jobs in the United States.

"The concerns over this sale are only one more reason showing the importance of congressional review and why it is deeply disturbing that the Trump administration is trying to circumvent the law and Congress to give the Saudis not only American jobs but also American weapons technology," Sen. Bob Menendez of New Jersey, the ranking Democrat on the Senate Foreign Relations Committee, said.

The co-production plan had raised eyebrows among some lawmakers more than a year ago when the administration first tried to secure approval for tens of thousands of precision-guided bombs to Saudi Arabia and the United Arab Emirates, a Democratic congressional aide told NBC News.

Menendez held up the sale of 120,000 precision-guided bombs for Saudi Arabia and the UAE last year because of numerous accounts of civilian casualties from Saudi-led air raids in Yemen. The senator has said the administration failed to persuade him that selling more of the so-called "smart" bombs would prevent more civilian deaths.

Human rights, U.N. investigators and aid groups have accused Saudi Arabia and its allies of striking civilian targets, including hospitals and schools, in indiscriminate bombing raids in Yemen since Riyadh launched an armed intervention against Houthi rebels in 2015. Congressional resistance to weapons sales to Saudi Arabia only grew after the killing last year of Saudi writer and Washington Post columnist Jamal Khashoggi at the Saudi consulate in Istanbul.

The Trump administration has defended the arms sale as a way of ensuring Arab allies can defend themselves amid an allegedly increased danger from Iran, and that Washington's credibility as a military partner was at risk if it did not deliver spare parts and other weapons promptly. U.S. officials privately have also said that maintaining arms sales helps Washington exert a constructive influence over the kingdom.

A State Department official, who was not authorized to speak on the record, said the production arrangement "is not something we would have licensed if we were not fully confident in both the Saudi ability to protect the technology, as well as the positive impact on the American defense industrial base."

Democratic Sen. Chris Murphy of Connecticut, an outspoken critic of U.S. support for the Saudi-led campaign in Yemen, condemned the production arrangement.

"To think that we would co-produce these bombs and in turn contribute to an arms race, regional instability, and civilian deaths is unfathomable," Murphy said. "Congress needs to put a stop to the way we do business with the Saudis and start acting like the senior partner in this relationship rather than succumbing to whatever the kingdom wants."

"A secretive monarchy that commits atrocities in Yemen, that murders dissidents and journalists and lies to the world about it, and that treats women as property is not one to which we should be giving some of our most sensitive military technology," Sen. Patrick Leahy, D-Vt., said.

The Paveway bombs can strike a target within 10 feet when fired from 40,000 feet, according to William Hartung, director of the Arms and Security Project at the Washington-based Center for International Policy, and will almost certainly be used in the war in Yemen. "The weapons are going to be put to use in a civilian slaughter," he said.

Displays of missiles stand at the Raytheon International Inc. chalet on day two of the Farnborough International Airshow (FIA) 2018 in Farnborough, U.K., on July 17, 2018. Simon Dawson / Bloomberg via Getty Images file

The deal fits in with Saudi Arabia's long term economic plan, Saudi Vision 2030, which calls for the country to dramatically increase its domestic arms production. "They are trying to build up their own military manufacturing base," Hartung said.

But the assembly of bomb parts in the kingdom raises security and proliferation questions for the United States, he added. "If they can master the production process, they could sell it."

The defense firm that makes the precision-guided bombs, Raytheon, based in Waltham, Massachusetts, said co-production deals in other countries were not unusual.

"Local work share is a common practice used in the majority of aerospace and defense exports around the world," spokesman Mike Doble said in an email. Raytheon has a number of other international co-production arrangements that are all approved by the U.S. government and adhere to U.S. arms export regulations, he said.

Doble added that production in Saudi Arabia will likely start within about two years after the U.S. government approves a manufacturing license.

People inspect the site of an airstrike by Saudi-led coalition in Sanaa, Yemen on May, 16, 2019. Hani Mohammed / AP

The long-term nature of a joint production plan with the Saudis also prompted criticism in Congress, as the administration had insisted the arms package had to be expedited given the "emergency" conditions in the Middle East.

"This is a long-term endeavor in Saudi Arabia. How is this an emergency? " one Democratic congressional staffer said.

In a memo last month explaining why the administration had declared an emergency to fast-track the arms sale, Secretary of State Mike Pompeo said that "Iranian malign activity poses a fundamental threat to the stability of the Middle East and to American security at home and abroad."

He added: "Current threat reporting indicates Iran engages in preparations for further malign activities throughout the Middle East region, including potential targeting of U.S. and allied military forces in the region."