Putin so upset over Biden's killer comments he moved 28,000 Russian troops to Ukraine border, report

Vladimir Putin was reportedly so angered when President Joe Biden called him a "killer" in his first sit-down interview after taking office, the Russian president left his quarantine, got a COVID vaccination and moved 28,000 Russian troops to the border with Ukraine.

"It was really a shock. And it changed his behavior a lot," argues Pavel Baev, a senior researcher at Norway’s International Peace Research Institute in Oslo.

Russian Bear bombers went into action, forcing NATO to scramble 10 jets to intercept the Russian warplanes flying over the North Atlantic Ocean last week, a rare show of force near the Arctic. On Monday, Putin quietly changed Russia’s constitution to allow him to stay in power until 2036. He would be 83 years old.

"Bluffing comes naturally to [Putin]. He is much more of a manipulator than he is a warrior," says Baev, in an interview with Fox News. "War is always a risk, always a gamble. So I think he is much more about showing off, about posturing, about kind of showing muscle than about going for the real thing," according to Baev, author of the Jamestown Foundation report War Scare is Putin’s Natural Element. "He is much more about gesturing, about signaling, messaging and all sorts of things than about starting a real war."

Putin is putting Biden on notice with a figurative "Your move, Joe!"

Facing sagging popularity at home, Putin has returned to a "hybrid war" with the U.S. "President Putin would love to see Russian-U.S. relations reduced to a mano-a-mano battle between him and President Biden," according to Timothy Frye, author of the new book "Weak Strongman: The Limits of Power in Putin’s Russia."

By testing the American and NATO response time with hypersonic weapons tests in the Arctic, a military build-up on the border with Ukraine and an ongoing crackdown on supporters of his main political opponent Alexei Navalny, now jailed and on a hunger strike, "Vlad the Terrible" is signaling he is back and goading the White House to respond.

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"The Russian government is responsible for his health and well-being. We will continue to monitor the situation closely," White House press secretary Jen Psaki told reporters.

Frye urges the Biden administration not to play Putin’s game: "Putin has come to increasingly rely on repression of his political opponents, and I take that as a sign of weakness rather than a sign of strength," Frye said in an interview with Fox News. "There's already a lot of Putin fatigue in the country. He's run the country for 20 years, and while he remains broadly popular, I think there is a desire within Russia, many elements of Russian society for political change."

So is Putin’s new war posture just a bluff? Some experts say it is bait for the Pentagon to spend more on expensive next-generation weapons.

"There is an arms race. There is competition with the new weapons system, including hypersonic, including nuclear, but again, the Russian economy is not the Soviet economy. Arms race is a very hard thing to sustain, particularly when you are competing with United States," Baev argues. "I don't think Putin has a long term horizon. He is much more about today and tomorrow and may be a little bit about the day after than about a sustainable arms race."

New satellite photos of expanding Russian military bases and weapons tests are raising fears of another "Cold War" buildup and a possible arms race in the Arctic. Allies say nuclear tests could devastate the delicate ecosystem. A series of recent weapons tests by Moscow and the alarming development of a stealth nuclear-powered megaton torpedo, that could devastate cities along the U.S. East Coast with radioactive tsunamis, has quickly gained the attention of the U.S. military.

When three Russian submarines burst through the Arctic ice in a synchronized exercise in late March, the Pentagon took notice and Putin praised the naval achievement. Each Russian sub can carry 16 ballistic missiles.

"We're monitoring very closely. Nobody wants to see the Arctic as a region become militarized," Defense Department press secretary John Kirby told reporters at the Pentagon.

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As rising temperatures and climate change cause the polar ice to melt, the world's Great Powers are in a race to control the Arctic and its new valuable sea lanes.

"Russia is refurbishing Soviet-era airfields and radar installations, constructing new ports and search-and-rescue centers, and building up its fleet of nuclear- and conventionally-powered icebreakers. It is also expanding its network of air and coastal defense missile systems, thus strengthening its anti-access/area-denial capabilities over key portions of the Arctic," according to Pentagon spokesman Lt Col Thomas Campbell, who notes that Russia recently established two permanent rotational Quick Reaction Alert detachments at two Arctic airfields.

Commercial satellite photos show Russia expanding its military bases in the Arctic — adding 50 posts that it shuttered at the end of the first Cold War.

Kremlin spokesman Dmitri Peskov says Putin sees the Arctic as a priority. "The economic potential is growing from year to year, you know that there are general plans for national development in the Arctic zone," which Russia needs for its oil and gas reserves and newly thawed shipping lanes which will shorten routes from Europe to Asia.

Experts worry the Russian Bear is seeking a "new Cold War" with the West by testing state-of-the-art weapons like a hypersonic anti-ship cruise missile launched by the Northern Fleet into the Barents Sea and developing the Poseidon -- an unmanned stealth nuclear powered cruise missile that can travel 6,000 miles along the sea floor.

"It is designed to be undetected, once exploded, it could devastate coastal areas in the United States," says Heather A. Conley, senior vice president for Europe, Eurasia, and the Arctic; and director, Europe, Russia, and Eurasia Program at CSIS.

Such hypersonic weapons seemed like a joke when Vladimir Putin first introduced a prototype to Russian lawmakers three years ago suggesting they could hit Mar-A-Lago. Now military experts are taking them seriously and spending vast budgets to develop their own.

"Think of it as an undersea drone that goes across the North Atlantic. And if it would explode radioactive explosion, it would sort of create a tsunami, if you will, along the East Coast radiating a massive amount of water and could do untold devastation to the United States," Conley said in an interview with Fox. 

Vice Admiral Robert Murrett is the deputy director of the Institute for National Security and Counterterrorism at Syracuse University and served as the director of the National Geospatial-Intelligence Agency for four years overseeing the Pentagon's top secret spy satellites until 2010. He says Russia is developing a series of weapons that are very concerning to the U.S. military.

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"The Arctic is a terrific shortcut, whether you're in an aircraft, whether you're underneath the surface of the ocean and also for intercontinental ballistic missile, this goes back to the Cold War," said Murrett, who has spent his career watching Russian military movements.

The U.S. Air Force recently deployed 4 B-1 bombers to an Arctic base in Norway for the first time, another sign that Putin is getting the response he wants: attention and a diversion from his domestic opponents.