Johnson approved the use of equipment from "high-risk vendors" — a term widely understood to mean Huawei — at a National Security Council meeting Tuesday but restricted the equipment to 35 percent in nonsensitive parts of the network, and said the government would impose certain restrictions such as excluding the technology from locations near nuclear sites and military bases.

“I think what we’ll likely do is bank this and say, ‘Thank you for the 35 percent cap. Thank you for the specific bans on all these functions of the network that Huawei cannot actually be happy with,'" a U.S. official told POLITICO.

Yet, the official said: "We don’t think ... you want to end up at 35 percent. You want it to be lower, given what will ride on 5G networks.” The official said the concern is that the attempt to mitigate the potential problems "leaves a significant amount of risk."

Republican lawmakers, however, were quick on Tuesday to condemn the U.K. decision.

"Here’s the sad truth: our special relationship is less special now that the U.K. has embraced the surveillance state commies at Huawei," Sen. Ben Sasse (R-Neb.) said in a statement. "During the Cold War, Margaret Thatcher never contracted with the KGB to save a few pennies."

"The decision by @BorisJohnson to allow Huawei into the UK’s telecommunications network is wrong, dangerous, and a grave shortsighted mistake," tweeted Rep. Elise Stefanik (R-N.Y.), a fierce Trump defender. "Congress must work on a bipartisan basis to push back on this decision by the UK to open their arms to China’s surveillance state."

Still, the British move is something of a blow to the Trump administration’s efforts to further curtail Huawei’s global reach and to limit its role in building 5G mobile networks.

U.S. officials have portrayed the Chinese company as a national security threat that could leverage its telecommunications equipment to effectively spy on foreign governments and citizens — an assertion that Huawei has repeatedly denied.

The White House was "disappointed" in the U.K. decision, a senior administration official said, though the person added that the U.S. will still work with Johnson on "a way forward" that excludes equipment from Huawei. "There is no safe option for untrusted vendors to control any part of a 5G network," said a senior administration official, who declined to be named, in a statement.

"We continue to urge all countries to carefully assess the long-term national security and economic impacts of allowing untrusted vendors access to important 5G network infrastructure," the administration official added.

Huawei executives have previously rebuked the broader U.S. campaign against the company as political posturing and suggested the company is a victim in the ongoing trade wranglings between Washington and Beijing.

“Huawei is reassured by the UK government’s confirmation that we can continue working with our customers to keep the 5G roll-out on track," Huawei Vice President Victor Zhang said in a statement. "This evidence-based decision will result in a more advanced, more secure and more cost-effective telecoms infrastructure that is fit for the future."

Some Democratic lawmakers painted the U.K.'s decision as a failing of the Trump administration, stating plainly that the U.S. has lost the ability to sway the decisions of other countries.

POLITICO NEWSLETTERS Morning Tech Technology news from Washington and Silicon Valley — weekday mornings, in your inbox. Sign Up Loading By signing up you agree to receive email newsletters or alerts from POLITICO. You can unsubscribe at any time. This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

"America has never been weaker. We have never had less influence," tweeted Sen. Chris Murphy (D-Conn.). "Not even our closest ally Britain, with a Trump soulmate in Downing Street, listens to us anymore."

The State Department has been traversing the globe warning countries that Huawei's gear and other Chinese-manufactured equipment could pose a national security threat by providing a tool for Beijing to effectively spy on foreign governments and citizens. Pompeo plans to visit the U.K. on Wednesday.

Trump administration officials have gone so far as to suggest that sharing sensitive intelligence with nations that use the technology could be restricted, a response that has already garnered the support of at least some Republican lawmakers on Capitol Hill.

But handicapping Huawei also has economic benefits for the U.S., particularly amid Trump’s call for an “America First” approach to international relations. The nation that most shapes the development of still-nascent 5G networks could gain a key advantage as the next wave of tech services and gadgets are created.

That reality has complicated the U.S. government’s pitch that other countries ought to exclude Huawei’s technology. While Japan, Australia and New Zealand have effectively banned its products, European nations that already use Huawei technology as part of their existing networks have been less keen to agree.

A person familiar with Huawei's thinking told POLITICO the Trump administration's campaign has "largely been a flop" and believes that now that the U.K. has rebuffed Trump, it eases the way for countries with key Huawei customers like Canada and Germany to do the same.

"Canada will be more likely to allow Huawei," the person said. "If the U.K. had blocked Huawei completely, it would have been very difficult for Canada. But I think this kind of opens the door for them, too."

Annabelle Dickson in London contributed to this report.

