Washington (CNN) The US government has obtained intelligence that Saudi Arabia has significantly escalated its ballistic missile program with the help of China, three sources with direct knowledge of the matter said, a development that threatens decades of US efforts to limit missile proliferation in the Middle East.

The Trump administration did not initially disclose its knowledge of this classified development to key members of Congress, the sources said, infuriating Democrats who discovered it outside of regular US government channels and concluded it had been deliberately left out of a series of briefings where they say it should have been presented.

The previously unreported classified intelligence indicates Saudi Arabia has expanded both its missile infrastructure and technology through recent purchases from China.

The discovery of the Saudi efforts has heightened concerns among members of Congress over a potential arms race in the Middle East, and whether it signals a tacit approval by the Trump administration as it seeks to counter Iran . The intelligence also raises questions about the administration's commitment to non-proliferation in the Middle East and the extent to which Congress is kept abreast of foreign policy developments in a volatile region.

The development comes amid growing tensions between Congress and the White House over Saudi Arabia.

Despite bipartisan criticism over the Kingdom's war in Yemen and its role in the murder of journalist Jamal Khashoggi, the White House has sought an even closer relationship with the Saudis, as evidenced by its recent decision to sell the Kingdom billions of dollars in weapons and munitions despite opposition in Congress.

While the Saudis' ultimate goal has not been conclusively assessed by US intelligence, the sources said, the missile advancement could mark another step in potential Saudi efforts to one day deliver a nuclear warhead were it ever to obtain one.

The Kingdom's Crown Prince, Mohammed Bin Salman, has made clear that should Iran obtain a nuclear weapon, Saudi would work to do the same, telling 60 Minutes in a 2018 interview that, "Without a doubt, if Iran developed a nuclear bomb, we will follow suit as soon as possible."

Though Saudi is among the biggest buyers of US weapons , it is barred from purchasing ballistic missiles from the US under regulations set forth by the 1987 Missile Technology Control Regime, an informal, multi-country pact aimed at preventing the sale of rockets capable of carrying weapons of mass destruction.

Yet the Saudis have consistently taken the position that they need to match Iran's missile capability and have at times sought help on the side from other countries, including China, which is not a signatory to the pact.

Saudi Arabia is known to have purchased ballistic missiles from China several decades ago, and public reports speculated that more purchases may have been made as recently as 2007. The Kingdom has never been assessed to have the ability to build its own missiles or even effectively deploy the ones it does have.

Instead, the Saudis' arsenal of Chinese-made ballistic missiles was a way to signal its potential military strength to regional foes, primarily Iran.

That, the sources told CNN, has shifted based on the new intelligence.

US-supplied air power

For decades, the US worked to ensure that Saudi Arabia had air supremacy in the region, largely through its purchases of American military aircraft, precisely so that it wouldn't seek to go around the US to upgrade its missile capabilities.

"Saudi Arabia needn't race Iran to produce or procure ballistic missiles. It already has a significant conventional military advantage," said Behnam Taleblu of the Washington-based think tank Foundation for Defense of Democracies.

But questions have arisen in recent months about whether that rationale still stands, particularly as the Trump administration has pulled out of the Iran nuclear deal and the Kingdom faces ballistic missile threats from Iran proxies in Yemen.

Satellite imagery, first reported by the Washington Post in January, suggested the Kingdom had constructed a ballistic missile factory. Analysts who viewed the images said they appeared to match technology produced by the Chinese.

Satellite imagery captured on November 13, 2018 shows a suspected ballistic missile factory at a missile base in al-Watah, Saudi Arabia. Image was initially discovered by Planet Labs and the Middlebury Institute of International Studies at Monterey.

A second image of the same missile facility obtained by CNN shows a similar level of activity at the site on May 14, 2019, according to Jeffrey Lewis, director of the East Asia Nonproliferation Program at the Middlebury Institute.

"Saudi Arabia's reported interest in domestic ballistic missile production should rightly raise eyebrows," Taleblu said. "Both the reported missile base and Riyadh's interest in a domestic fuel cycle indicates, however nascent, a desire to hedge against Iran."

The CIA and the Office of the Director of National Intelligence declined to comment on any intelligence related to Saudi Arabia's ballistic missile activity or whether the US believes the Kingdom is contracting in that area with foreign partners.

A spokesman for the Saudi Embassy in the US did not respond to a request for comment.

In a statement, the Chinese Foreign Ministry said that China and Saudi Arabia are "comprehensive strategic partners," and that both countries "maintain friendly cooperation in all areas, including in the area of arms sales. Such cooperation does not violate any international laws, nor does it involve the proliferation of weapons of mass destruction."

A State Department official declined to comment on classified intelligence matters, but told CNN that Saudi Arabia remains a party to the Nuclear Nonproliferation Treaty and has accepted an obligation never to acquire nuclear weapons. The spokesperson also pointed to a recent statement by a US State Department official reaffirming the US commitment to "the goal of a Middle East free of weapons of mass destruction and delivery systems."

Sources said there has been no indication from the administration that there has been an explicit policy shift as it relates to non-proliferation of ballistic missiles in Saudi, but noted the administration's awareness of the intelligence -- and lack of concrete action to halt the advances since it was obtained.

Beyond satellite imagery

US intelligence agencies constantly monitor foreign ballistic missile development and the flow of materials around the world. Related intelligence is analyzed on a daily basis and any significant change would likely make it into the Presidential Daily Briefing, according to two former senior US intelligence officials.

The Senate Intelligence Committee has been given access to the Saudi intelligence, though it has not received a specific briefing on the subject, according to two sources familiar with the matter.

But the Senate Foreign Relations Committee, which has oversight of the State Department and US foreign policy broadly, learned about the Saudi intelligence earlier this year only after it was discovered by Democratic staff on the committee, including in one instance when a staff member on an unrelated trip to the Middle East was informed of details through a foreign counterpart, two of the sources told CNN.

There had already been at least two classified briefings on issues related to the topic where the information could have been disclosed to senators, according to one source.

When the staff brought the new information to the panel's top Democrat, Sen. Robert Menendez of New Jersey, he immediately requested-- and was granted-- a classified, senators-only briefing for committee members on the details, a rare occurrence that underscored the importance of the discovery and the administration's failure to initially brief the committee on the matter.

Several sources said the analysis presented in the classified briefing, held on April 9, went far beyond the January Washington Post story about the satellite images, and provided concrete evidence that Saudi Arabia has advanced its missile program to a point that would run in direct conflict with long-established US policy to limit proliferation in the region.

The day after the classified briefing, Secretary of State Mike Pompeo testified publicly in front of the committee as part of a routine hearing on the State Department budget.

Over the course of a few hours, the dispute over intelligence sharing began to spill out into the open, turning a relatively benign budget hearing into a debate over a potentially crucial shift in US policy over missile proliferation in the Middle East.

Though at the time, it was hard to notice.

Without going into specifics, Menendez castigated Pompeo for the administration's decision not to share classified information with the committee until it was brought to the administration by the senator himself.

"That's simply unacceptable," Menendez told the country's top diplomat, adding that if Congress is to perform its constitutional duties, the State Department "needs to do a better job of engaging with us, briefing us and responding to our requests."

Later in the hearing, three other Democratic senators obliquely referenced the issue in their questions to Pompeo, citing public reports related to Saudi ballistic missile ambitions.

JUST WATCHED Sen. Kaine asks Pompeo about Saudi missiles Replay More Videos ... MUST WATCH Sen. Kaine asks Pompeo about Saudi missiles 01:15

Neither the senators nor Pompeo mentioned the previous day's briefing, or that their questions or answers were based on specific intelligence.

But in hindsight, the exchanges shed light on the Trump administration's hardline position that countering Iran is the ultimate priority in the region -- regardless of long-held US non-proliferation positions.

In his responses, Pompeo made clear the administration's preference that Saudi Arabia buy US technology, a possible nod, multiple US officials said, to internal opposition inside the Trump administration to restrictions on US sales of ballistic missiles to the Kingdom.

"There've been those who've urged the United States to take a different posture with respect to Saudi Arabia, not to sell them technology," Pompeo said. "I think you see the risks that are created. It would be better if the United States was involved in those transactions than if China was."

While Pompeo acknowledged under questioning that it is still US policy to oppose proliferation of ballistic missile technology in the Middle East, a telling exchange occurred later.

JUST WATCHED Sen. Udall asks Pompeo about Saudi and Chinese missiles Replay More Videos ... MUST WATCH Sen. Udall asks Pompeo about Saudi and Chinese missiles 01:50

Sen. Tom Udall, a New Mexico Democrat, citing the Washington Post report on the satellite images, asked what the US was doing to prevent foreign sales of ballistic missile technology to Saudi Arabia.

Pompeo made clear, intentionally or not, a prevailing administration position that has guided much of its policy in the region -- including its knowledge of the expanding Saudi ballistic missile program.

"This is certainly something that we all need to keep an eye on," Pompeo said, before adding that "most of the folks who are working to build out missile systems" were doing so in direct response to Iran's ability to continue to enhance its missile program under the 2015 nuclear accord.

"Others are doing what they need to do to create a deterrence tool for themselves," Pompeo said. "It's just a fact."

Udall, who a source confirmed had been in the classified briefing the day prior, responded after a pause by pressing the administration to stick to the long-held US policy to deter missile proliferation in Saudi "Well, I very much hope that the administration will push back in terms of what's happening in missiles across the Middle East."

Tensions over Saudi policy

The new revelations come at a particularly fraught time in the Saudi-U.S. relationship.

Last year, as evidence of the Saudi government's role in the murder of Khashoggi emerged, GOP Senators including Sen. Lindsey Graham of South Carolina and then-Foreign Relations Chairman Bob Corker of Tennessee publicly condemned the Trump administration's timid response.

"There's not a smoking gun, there's a smoking saw," Graham said after emerging from a classified briefing in December, referring to reports that the Saudi team had included a forensic expert who arrived in Turkey with equipment to dismember Khashoggi's body.

In an interview with Axios on HBO that aired on Sunday , Trump's son-in-law and senior adviser Jared Kushner refused to go into details about his private conversations with the Saudi crown prince, and maintained that the Saudis are a key ally in helping the US contain Iran.

Asked whether he would join Khashoggi's fiancée in calling on the Saudi government to release Khashoggi's body, Kushner demurred, saying the decision "would be up to the Secretary of State" and that "we'll do everything we can to try to bring transparency and accountability for what happened."

Anger over the administration's handling of the Khashoggi murder led to bipartisan support for resolutions to end US involvement in the war in Yemen, where the Saudi-led coalition has been accused of indiscriminately bombing civilians. The conflict has resulted in widespread famine and put an estimated 14 million people at risk of starvation , according to the United Nations.

In March, lawmakers pushed through the House and Senate a measure that would've forced Trump to get permission from Congress before allowing the US military to aid Saudi Arabia in its fight against Iran-backed Houthi rebels in Yemen. Lawmakers were ultimately unable to override Trump's veto

Tensions between the administration and lawmakers were again exacerbated by the administration's May 24 announcement that it would declare an emergency over escalating tensions with Iran in order to bypass Congress to complete an $8.1 billion sale of weapons, munitions, intelligence and maintenance to various countries including Saudi Arabia and UAE.

A bipartisan group of seven senators, including Menendez and Graham, on Wednesday said they were introducing resolutions to block all 22 arms sales tied to the administration's move.

There is also an ongoing bipartisan effort to finalize a new sanctions package targeting Saudi Arabia -- one opposed on its face by the Trump administration, which tends to cast its view of the Kingdom as a binary choice: you either support Saudi Arabia or you support Iran.

For Sen. Chris Murphy, a Connecticut Democrat on the Senate Foreign Relations Committee and sharp critic of the administration's Saudi policy, the choice is not that simple when it comes to ballistic missile proliferation.

"I think it's a total misread of the region to think that the Saudis are the good guys in this equation. The Iranians do really awful things in the region. But so do the Saudis. "

Murphy declined to comment on the Saudi missile intelligence he received during the April 9 briefing, but was willing to address the broader issue, including the long-term implications should the US abandon its policy of missile deterrence in the Middle East.

"For decades the US has had a policy of trying to quell, not ignite an arms race in the Middle East, and for good reason," said Murphy. "It stands to reason we would want less weapons pointed at each other."

'It was egregious'

The whole incident puts the panel's Republican chairman, Sen. Jim Risch of Idaho, in a tricky spot. Compared to his predecessor Corker, an avid Trump critic, Risch has refrained from criticizing the administration, and has attempted to strike a balance between tending the concerns of angry committee members while also trying not to undercut Trump's foreign policy strategy.

Risch, who also sits on the Senate Intelligence Committee, dismissed complaints that the intelligence omission was intentional and chalked it up to a simple oversight, given the sheer volume of information the intelligence community gathers each day.

"There's no doubt that factual matters that the intelligence community has sometimes don't get into the hands of senators simply because there is too much of it," Risch told CNN, noting that he hadn't received any complaints from Republican members of the panel. "It's not intentional at all. It's just simply that it can't be done."

Menendez doesn't buy into that theory.

"You can't lose track of something like this," said Menendez, who would not discuss the topic of the underlying intelligence at issue. "It was egregious."

Menendez is now pressuring the administration to provide a classified briefing on the issue for all 100 senators.

While frustrations over access to classified information by the Senate Foreign Relations Committee go back years, they have become particularly acute during the Trump administration, senators and aides interviewed for this story said.

"I think our [intelligence community] knows a lot and they don't want to tell us," said Democratic Virginia Sen. Tim Kaine, who declined to address the specific subject matter. Kaine noted that there are a series of issues -- several related specifically to Saudi, including authorizations to sell civilian nuclear technology to the country -- that have remained shrouded in secrecy, despite repeated requests to the administration to provide briefings or documentation.

Kaine on Tuesday revealed for the first time at least two of the technology sales occurred after Khashoggi's murder, including one that was finalized just 16 days after the journalist was killed in the Saudi consulate in Istanbul.

The divide between Congress and the administration on Saudi has led to increasingly hostile receptions for Trump officials who come to Capitol Hill to testify. It's also one that has largely left the US public in the dark as to the administration's actions with its closest allies in the region.

For at least one Democratic Senator who spoke on condition of anonymity even as he declined to address the underlying Saudi intelligence, it's all part of a broader trend of the administration refusing to share intelligence with Congress.

The administration "has taken a position of: you don't need to know anything," the senator said. "Which, of course, is constitutionally inaccurate."