When it comes to U.S. national security, one foreign company sets off alarm bells like no other: Huawei, the Chinese telecom giant.

Huawei scored a key victory, and the U.S. suffered a significant setback, when the company received the green light to build up to 35% of Britain’s 5G cellular phone network.

“This is a major loss for American national security, foreign policy and technology policy,” said Peter Singer of the New America think tank in Washington.

The Trump administration has lobbied hard with U.S. allies, urging them not to buy from Chinese firms.

“It’s critical that European countries not give control of their critical infrastructure to Chinese tech giants,” Secretary of State Mike Pompeo wrote last month in an op-ed for Politico. “Just consider Huawei’s track record. … It is implicated in espionage in the Czech Republic, Poland and the Netherlands, [and] has allegedly stolen intellectual property from foreign competitors in Germany, Israel, the United Kingdom and the United States.

David Edelman was on the National Security Council under President Obama and now runs MIT’s Internet Policy Research Initiative. He puts it this way: “The administration’s case goes like this. They say first that Huawei equipment is generally less secure than its competitors. Second, that Chinese security services might find it irresistible to try to steal secrets. Third, and maybe most dramatically, if there were ever a major conflict, Beijing might use that access to remotely shut down critical systems.”

Britain says it decision is based in part on working with Huawei for years on its existing cellular system. Britain also believes it can manage the risk by limiting Huawei to the periphery of the new network — things like base stations and antennas that mostly pass on data — and keeping it away from the more sensitive network core.

This 5G network hasn’t yet been built, and the U.S. hasn’t yet given up making its case. Pompeo was in Britain on Wednesday and said he would continue to stress U.S. security concerns.

“The real question here is whether we’ve crossed a particular Rubicon, whether by having this Chinese content in the underlying 5G network, that effectively it’s a decision that can’t be reversed,” Edelman said.

Which brings us to the second big issue — the global technology competition.

For many in the West, China is viewed as a giant factory that puts together iPhones. But the latest development means it’s now been cleared to help build a cutting-edge network in Western Europe.

5G is being billed as revolutionary. Data will move a lightning speed, driverless cars will communicate with each other, doctors will perform surgery remotely. And China is now considered at the forefront.

“China is today a major player in the technology market,” said Beau Woods, who studies cyber issues at the Atlantic Council in Washington. The British decision, he added, “is a big win for China’s prestige and also kind of puts other nations, other companies, on notice that China’s not just the packaging and assembly hub of the world anymore.”

China’s stated goal is to be a world leader in the most important technologies of the 21st century. To this end, the government supports Huawei and other tech companies in ways that Western countries don’t, said Dean Cheng with the Heritage Foundation.

When it comes to 5G, he said, Huawei offers the complete package, something Western firms can’t match at this point.

“They offer essentially soup to nuts,” Cheng said. “That’s a huge advantage in terms of the whole system being integrated. It presumably works well with each other. Also, it is significantly cheaper than any of the partial competitors out there.”

All this makes it harder on the third big issue — U.S. foreign policy. The Trump administration has pressed American allies to keep Chinese hardware out of their sensitive networks. The results have been mixed at best.

“If you’re not getting your closest intelligence partners on board, how can you expect to get the rest of Europe or Latin America, Africa?” Peter Singer asked. “The thing to watch for is the dominoes falling. All the other states that have been holding back, may be saying, ‘OK, the Brits are going this way now. We can, too.'”

Just a day after the British decision, the European Union on Wednesday recommended limiting, but not banning, “high-risk” companies. Huawei said it welcomed the decision and hopes to be part of a fast, secure 5G network across Europe.

Greg Myre is an NPR national security correspondent. Follow him @gregmyre1.

Senators weighing impeachment charges against President Trump will spend Thursday firing off questions to trial lawyers, as they did the day before, just as the specter of John Bolton’s appearance as a witness continues to stoke speculation.

Republicans would like Trump to be acquitted as soon as Friday, but Democrats are working behind-the-scenes to recruit enough conservatives to support bringing in witnesses to testify.

That effort is flagging, senators say.

“The momentum is clearly in the direction of moving to final judgement on Friday,” said Sen. John Barrasso, R-Wy. “We still have a couple members who said they want to listen to answers to questions, but that’s where the momentum is in the caucus right now.”

Sen. Chuck Schumer, D-N.Y., gave this assessment on where the votes stand on possibly bringing in witnesses: “Probably no,” Schumer told reporters. “But is it a decent, good chance? Yes.”

Democrats need to convince at least four senators to cross party lines in order to lock in enough votes to subpoena witnesses. And while a handful of moderate Republicans have indicated they are open to hearing from witnesses, the prospect of Democrats successfully enlisting enough conservatives to join their witness push looked increasingly dim. Democratic leaders have even conceded that it now appears unlikely.

Meanwhile, Republicans spent some time on Wednesday saying that that once the door is open to witnesses, Republicans would like to call individuals including Joe Biden’s son, Hunter, who had served on a Ukrainian energy company board and the anonymous whistleblower whose intelligence community complaint about Trump’s July 25 call with the Ukrainian president set the impeachment process into motion.

Asked what kind of delay witnesses would add to the trial, Trump defense lawyer Jay Sekulow said: “months.”

Sekulow added: “This would be the first of many weeks.”

Schiff bristled at this argument, saying Trump’s defense team is exaggerating the delay in order to discourage senators from supporting calling witnesses, including the former National Security Adviser John Bolton, whose possible appearance in the trial has captured Washington since revelations from his forthcoming book were publicly leaked.

“You can subpoena John Bolton,” Schiff said. “Don’t be thrown off by this claim, ‘oh if you even think about it, we are going to make you pay with delays like you’ve never seen, we’re going to call witnesses that will turn this into a circus,” Schiff said. “It shouldn’t be a circus. It should be a fair trial. You can’t have a fair trial without witnesses.”

Some Republicans have been discussing a possible deal involving a witness-for-witness swap. Some conservatives were entertaining the idea of calling Hunter Biden as their witness.

Sen. Lindsey Graham, R-S.C., said if Republicans are able to call just one witness it will be Hunter Biden.

“Because he’s incredibly relevant to whether or not President Trump had a reason to believe that corruption was afoot in the Ukraine,” Graham told reporters on Wednesday.

Over eight hours of debate Wednesday, Democratic House managers and Trump’s defense made their final pitches ahead of a key vote on Friday on whether the Senate will hear from witnesses.

White House lawyer Pat Philbin defended accepting “credible” information from foreign sources about someone running for public office, arguing that “mere information is not something that would violate the campaign finance laws.” Democrats, including impeachment manager Rep. Adam Schiff and several senators, quickly lashed out. Schiff called that policy “corruption.” Sen. Debbie Stabenow said Democrats were in “shock” hearing the defense and Sen. Mark Warner said he was “flabbergasted.”

Also among the more striking responses was to a question posed by Sen. Ted Cruz, R-Texas, who asked whether a president ordering a quid pro quo in the foreign policy arena was ever appropriate.

The question was relevant to the heart of the articles of impeachment, which center on an allegation that Trump conditioned hundreds of millions of dollars in military aid to Ukraine on the country announcing investigations into Trump’s political rivals. In other words, Democrats are accusing Trump of abusing his office by using a quid-pro-quo scheme to improve his chances of re-election.

Alan Dershowitz, one of Trump’s lawyers, took the sweeping view that if a quid pro quo is in the president’s “electoral interest” than it should never result in an impeachment, a broad interpretation of the powers of the executive branch.

“If a president does something which he believes will help him get elected in the public interest, that cannot be the kind of quid pro quo that results in impeachment,” Dershowitz said.

Dershowitz said if a president does not act out of purely a “corrupt motive,” but rather has a “mixed motive,” meaning a president is acting of the country’s interest and in hopes of improving re-election prospects, than the behavior cannot warrant articles of impeachment.

“How many presidents have made foreign policy decisions after checking with their political advisers and pollsters?” he asked.

Sen. Richard Blumenthal, D-Conn., called that argument brought Dershowitz “into the land of legal absurdity,” he tweeted. “That anything a public official does for re-election is OK. That cannot be true.”

Evaluating the first of two days’ of question-and-answers, Sen. Bob Casey, D-Pa., said he did not think the day’s proceeding changed any minds.

“I don’t think so in large measure, but it does force everyone to confront issues that sometimes you haven’t thought as much about or sometimes you are familiar with, but not to the level of depth that you should,” Casey said.

With a strong Republican majority in the Senate, Trump is expected to be acquitted.

NPR’s Brakkton Booker and Lexie Schapitl contributed to this report.