The anonymous whistleblower whose complaint prompted the impeachment inquiry into President Trump has agreed to answer written questions under oath from House Republicans. The offer came as President Trump called on Sunday for news organizations to identify the name of the whistleblower.

Mark Zaid, an attorney for the whistleblower, confirmed to NPR that an offer has been made to the House Intelligence Committee to open a direct channel between the whistleblower and Republicans as long as the questions do not compromise the individual’s identity. All of the whistleblower’s answers would be made under penalty of perjury.

It is not clear, however, if Republicans will take Zaid up on the proposal.

“Receipt acknowledged,” Zaid told NPR, saying House Republicans have confirmed they received the offer. “No substantive response yet.”

On CBS’s Face the Nation, House Minority Leader Kevin McCarthy, R-Calif., suggested written testimony would not satisfy Republicans.

“When you’re talking about the removal of the president of the United States, undoing democracy, undoing what the American public had voted for, I think that individual should come before the committee,” said McCarthy. “He needs to answer the questions.”

Trump has also been demanding that the whistleblower sit for questioning, alleging that the whistleblower was politically motivated. That claim has been denied by the whistleblower’s legal team.

“Being a whistleblower is not a partisan job,” Zaid tweeted on Sunday. “Nor is impeachment an objective. That is not our role.”

News of the whistleblower’s offer to provide written testimony came three days after the House voted to formalize the impeachment inquiry into President Trump and set in motion a timetable for public hearings.

Since the start of the inquiry in September, House investigators have spoken to roughly a dozen witnesses about the president’s efforts to pressure the government of Ukraine.

According to a White House summary of the now infamous July 25 call, Trump asked Ukrainian President Volodymyr Zelenskiy for help investigating unsubstantiated allegations of corruption against former Vice President Joe Biden and his son. The president also sought assistance investigating a debunked conspiracy theory accusing Ukraine of involvement in the 2016 hacking of the Democratic National Committee — an attack U.S. intelligence has traced to Russia. The call took place as nearly $400 million in U.S. aid for Ukraine was up in the air.

Trump has repeatedly denied any wrongdoing or a “quid pro quo.”

“The whistleblower gave a very inaccurate report about my phone call,” Trump said on Sunday. “My phone call was perfecto.”

In recent days, Republican allies have escalated their attacks on the impeachment process, decrying a process they say is unfair to the president and lacking in transparency. Some of the president’s allies are also now openly speculating on the identity of the whistleblower.

On Sunday, Trump pleaded with the news media to disclose who the whistleblower is, arguing that the person’s account of Trump’s call with the president of Ukraine is incorrect.

“They know who it is. You know who it is. You just don’t want to report it,” Trump told reporters. “And you know, you would be doing a public a service if you did.”

Federal law protects whistleblowers in the intelligence community from retaliation and shields their identity, as long as they follow procedure to ensure that classified information is not divulged.

The whistleblower’s legal team has maintained that disclosing their client’s name places the individual and their family in physical danger.

Since the whistleblower’s complaint was filed, the whistleblower and the person’s legal team have received death threats, according to Zaid.

House Democrats involved in the impeachment proceedings have said that the whistleblower’s testimony is no longer critical to the inquiry, since the account has now been confirmed by former White House aides and other witnesses before the three committees leading the investigation.

There are precisely 525 stairs from the icy waters of the Barents Sea to the top of the observation post in the far northeast corner of Norway, along the Russian border. It’s a steep climb, but once you reach the apex, there’s a good chance one of the young Norwegian conscripts manning the outpost will have a platter of waffles — topped with strawberry jam and sour cream, a Norwegian favorite — waiting.

The border post, OP 247, offers a commanding view of this starkly beautiful area some 250 miles above the Arctic Circle. To the east, on the other side of the border, is a Russian observation post and a coast guard facility. Directly ahead, across the Barents Sea, is the small Norwegian island of Vardo, which houses a U.S.-funded military surveillance radar system.

“Apparently it’s annoying the Russians a lot,” says Capt. Sigurd Harsheim, commander of Jarfjord border company, because the radar installation helps keep an eye on Russian movements in the High North. “Basically you have good control of the entire Barents Sea and everything around it … and I think part of the irritation is that it’s American built.”

There’s good reason recently to keep a line of sight on Russia, whose sheer land mass overwhelms the seven other Arctic nations. Warming temperatures are opening up shipping lanes and uncovering the polar region’s abundant natural resources. And now several nations are engaging in a military buildup of the Arctic. Russia is upgrading its military capabilities with new fighter jets and navy vessels, and its submarines are pushing farther into the North Atlantic. Norwegian military officials say Russia is also carrying out cruise missile tests and live-fire military exercises. That is forcing its neighbor, Norway, and other NATO members to rethink their military strategy in the region.

“[The Russians] are rebuilding the Northern Fleet, building new submarines; they’re flying more; they are exercising more in the northwest of Russia with their battalions,” Norwegian Defense Minister Frank Bakke-Jensen tells NPR.

The center of Russia’s Arctic military activities is the Kola Peninsula, in the far northwest of the country, next to Norway. “Out on the Kola Peninsula … you’ll see that … they’re modernizing and rebuilding and also building new facilities,” says Maj. Brynjar Stordal, a spokesman for the Norwegian Joint Headquarters. “There’s a lot more activity and more new equipment. And we also see that the tactics are becoming more advanced.”

The heavily militarized Kola Peninsula is also a base for the Russian navy’s Northern Fleet, says Thomas Nilsen, a journalist who covers the region for the Independent Barents Observer online newspaper, based in Kirkenes, Norway.

“This is the home of the nuclear-powered submarines. This is the home of the [Russian] Spetsnaz special marine forces,” Nilsen says. He says the Kola Peninsula is also a key training area for Russia’s new weapons such as nuclear-powered cruise missiles and the nuclear-powered underwater drone.

Nilsen says Russia’s buildup is due in part to its deteriorated trust with the West and to protecting military assets in the High North, including its natural resources. Ninety percent of Russia’s natural gas exports come from Yamal Peninsula in the Arctic.

“We always have to remember that for Russia, the Arctic is economically and enormously important,” Nilsen says. “So the Arctic has a much stronger role in Russia’s national thinking than in any of the other Arctic states, including Norway.”

The Russian government, meanwhile, has long expressed concerns about NATO’s expansion near its borders. In June 2018, the Russian Embassy in Oslo complained that a Norwegian request for more U.S. troops “could cause growing tensions, triggering an arms race and destabilizing the situation in northern Europe.”

Still, the extent of Moscow’s aggression in the region has taken Western nations by surprise. In the years after the 1989 fall of the Berlin Wall and the end of the Cold War, the U.S. and NATO shuttered Arctic bases and moved weaponry and other assets out of the region. The Arctic region was peaceful, as Russia stopped being a concern, says Col. Joern Erik Berntsen, the commander of Norway’s Finnmark Land Defense. That changed in 2014 when Russia annexed Crimea.

“The operations in the Ukraine was kind of a game-changer for NATO and for us,” he says. “The security situation in the world has definitely changed; we are more or less back where we were before the fall of the wall.”

Berntsen says after Russia’s actions in Crimea, Norway needed to reexamine its security situation. It went on a buying spree, acquiring submarines from Germany and dozens of F-35 fighter jets from the United States. Norway is also rebuilding and rearming some of its own bases.

One of those is Porsangermoen, the world’s northernmost military camp, set among rolling hills and ponds in the county of Finnmark. In October, about 1,400 Norwegian troops carried out military exercises at the camp. There was snow on the ground, and a cold wind sliced through layers of clothing. Part of their training was how to fight under winter conditions.

“Fighting during winter conditions is probably the hardest you can do,” says Platoon Commander Lt. Benjamin Thompson. “That demands a lot of training.”

Thompson, wearing a partially white camouflage uniform, says he has also had to train U.S. troops that have been rotating into the country over the past couple of years. The U.S. has hundreds of service members, mainly Marines, stationed farther south in Norway.

“They were struggling in the beginning but after a while they became really good and learned a lot of important things to do during wintertime to be able to survive,” he says.

Norway has lobbied the U.S. and other NATO allies for a stronger presence and more military exercises in the Arctic. Last year, Norway was the key staging ground for Trident Juncture, one of the NATO’s biggest military exercises since 2002.

Two years ago, NATO reestablished an Arctic command, now out of Norfolk, Va., and the U.S. Navy recommissioned the 2nd Fleet to counter Russian activity in the North Atlantic.

Norway’s defense minister, Bakke-Jensen, is pleased. “We have been working through NATO and with the U.S. to bring attention back to the North Atlantic, to these areas,” he tells NPR. “We are satisfied with the new command structure; we are satisfied with the command control in Norfolk.”

In September, the U.S. flew a B-2 stealth bomber over the Arctic. James Townsend, who spent two decades working on NATO policy at the U.S. Department of Defense, says the mission helped send a signal to the Russians.

“The B-2 was showing that we can fly up there and showing the Russians that we will fly up there,” he says. “It was a training thing on the one hand, but it’s also a deterrent message to the Russians too.”

Townsend, now with the Center for a New American Security, says it is important for the U.S. to know what’s going on in the Arctic, but not get spooked by Russia’s buildup.

“What we don’t want to do is to back into a military conflict or military arms race, or back into militarization of the Arctic if we don’t have to,” he says.

Berntsen of the Finnmark Ground Defense says too large a U.S. military presence in the Arctic could provoke Russia. For now, he says, it is best to build up Norway’s forces and be ready to defend itself from its eastern neighbor.