Washington (CNN) The US government is conducting a training program with the government of Saudi Arabia to aid them in standing up an air marshal program similar to that of the United States.

In the coming years, Saudi-operated air carriers could fly around the world -- including to the US -- with US-trained armed security personnel on board.

The program was reviewed and considered during the Obama administration, but Transportation Security Administration officials did not have enough time to solidify its details by the end of 2016, according to officials who worked on it at the time. The training program was formally approved in March 2017 when John Kelly, then Secretary of Homeland Security, signed off on it, according to sources familiar with the program.

Its cost is unknown but the Saudis are reimbursing the US for the majority of the tab, according to multiple sources familiar with it.

A TSA team of at least seven officials have made trips to Saudi Arabia, where the training is expected to take place. The former deputy director of the federal air marshals is assigned to lead the program full-time. The plan would be for a few TSA personnel to be based in Saudi Arabia as the program matures, according to sources familiar with it.

The Saudis requested that the TSA engage in an aviation security project through the State Department given that there is a "Technical Cooperative Agreement" between the two countries which was established in 2008, a TSA official told CNN.

The technical agreement between the US and Saudi Arabia enables reimbursement of "technical knowledge, advice, skills and resources from US to the Kingdom of Saudi Arabia," explained a TSA official. That agreement, which was extended in 2013, won't expire until 2023.

"In support of a Department of State initiative with the Kingdom of Saudi Arabia, TSA is contributing aviation security guidance and technical advice to assist Saudi Arabia in strengthening their aviation security capabilities," a TSA spokesperson told CNN.

The program is raising concern among a handful of lawmakers on Capitol Hill, particularly in the wake of the Jamal Khashoggi murder, which has fueled a broader skepticism across Washington over the US-Saudi strategic partnership.

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There are also long-held concerns over Saudi Arabia's role in the 9/11 attacks. According to a portion of the 9/11 commission, which was declassified in 2016 , some of the hijackers, many of whom were Saudi citizens, may have had a relationship with the Saudi government.

"When you start talking about aviation security and putting armed Saudi government agents on airplanes coming to the US, you are really getting at the heart of why DHS and TSA were created in the first place," said a US government official familiar with the program.

Saudis crack down on terrorism

In recent years, the Saudi government has made a concerted effort to fight terrorism and extremism. They are specifically seeking to take it on with Riyadh's Global Center to Combat Extremism, which was launched in 2017.

Though Saudi Arabian airlines don't historically have a trend of having in-flight security problems, the Saudis do operate commercial planes in proximity to terrorist groups.

"The Saudis themselves face a significant terrorist problem, coming from al Qaeda, the Islamic State, and associated movements. So having air marshals makes perfect sense," said Daniel Byman, a senior fellow at the Brookings Institution, who says that Iran could also be threat. "As an American who has been in Saudi Arabia, I would like to see security on Saudi airlines around the world. It is good for everyone."

In 2000, two Saudi citizens hijacked a Saudi-operated flight flying from Jeddah to London.

In-flight security since 9/11

In the nearly two decades since 9/11, the US has overhauled in-flight security, at home and abroad. The breadth of those projects has been vast -- and not just related to air marshal training.

Last year alone, TSA worked with 23 other partner countries to improve their in-flight safety practices, a TSA spokesperson told CNN, who added that since 2002, TSA has had 87 training-related engagements with 39 countries - providing inflight security officer training to 19 countries, and general engagements with 20 additional countries.

The TSA would not, however, list the counties they are working with or describe the partnerships in detail.

"Due to the need to protect law enforcement/security information, TSA does not discuss specifics about its foreign training program including training content, staffing levels, and financial information," a TSA spokesperson told CNN.

A former top TSA official explained that when officials were discussing the Saudi program, there were conversations about sharing basic information such as protecting cockpits and how to maintain proficiency with the grueling hours of being an air marshal. There were still elements of the US air marshal program that, at the time, they did not intend to share.

"We made it clear that we were not going to share any specific tactics, techniques or procedures with the Saudis during my tenure," the official said. "You talk about what it means to protect an aircraft and what parts are vulnerable, without giving away secrets. That is what we did with even our closest allies."

Washington skepticism

Nationally, the US Federal Air Marshal Service has been in the limelight for wasting half of their budget, according to a report released in February by the Department of Homeland Security inspector general. The report "identified $394 million in funds that could be put to better use." Given those problems, some members of Congress have questioned why the US would export a flawed practice.

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Secretary of Homeland Secretary Kirstjen Nielsen was asked about the Saudi program during a hearing with the House Homeland Security Committee in March. She did not confirm or deny that the program exists, but promised a briefing on the matter. The committee is now working with the TSA to get that briefing scheduled.

As they wait, lawmakers are anxious to learn more. They cite specific concerns due to the Trump administration's close relationship with the Saudi kingdom.

"The Saudi government murdered Jamal Khashoggi and repeatedly lied about it. It is extremely concerning that the Trump administration would provide potentially sensitive information to such a despicable regime," Nevada Democratic Rep. Dina Titus told CNN. "It is disturbing that the Trump Administration continues to hide basic facts about its foreign policy from Congress and the American people."

Titus, who has been working to uncover the details of the program, asked Pompeo about reassessing the program during a hearing on Wednesday. Pompeo said he was not familiar with it. The Secretary promised to look into it, but tried to punt questions to the Department of Homeland Security, even though the agreement between the US and Saudi Arabia which enables this program was done through the State Department.

"I don't have responsibility for TSA," Pompeo said. "I think most appropriately DHS would be the best place to lodge those questions. But I am happy to take a look at them and see if they have important State Department equities or foreign policy elements to them."

Others point out that other US allies in the region already have air marshal programs, including Jordan. The Saudis should want parity, said Byman of Brookings.

Though the relationship has strengthened under the Trump administration, the US alliance with Saudi Arabia stretches back decades. The kingdom has been a key ally in the Middle East, particularly during the US war on terror.

President Donald Trump stopped in Riyadh on his first international trip in 2017 and signed a nearly $110 billion defense deal with Saudi Arabia's King Salman bin Abdulaziz Al Saud.

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The administration has come under fire, including from Republican members of Congress, over its response to the Khashoggi murder and the role Crown Prince Mohammad bin Salman could have played. This month, the Senate voted to pull US support for Saudi Arabia's war in Yemen, a move widely seen as a rebuke of the administration's position toward Saudi Arabia

Trump's cabinet members have warned of making any drastic changes to undermine their effort to shore up US-Saudi partnership in the wake of Khashoggi. Secretary of State Pompeo wrote that "degrading U.S.-Saudi ties would be a grave mistake for the national security of the U.S. and its allies," in a Wall Street Journal oped at the end of last year.

The State Department did not reply to a request for comment on this story. But the department lauds the fruits of the US-Saudi partnership on their website, especially when it comes to fighting terrorism.

"As a result of U.S. security cooperation, the Kingdom has foiled numerous terrorist attempts against Saudi and foreign targets, and has been able to successfully deter external attacks," writes the State Department, citing US-Saudi cooperation on maritime security, military preparedness, arms transfers, and cybersecurity.

This story has been updated