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There is growing concern in the White House and the Pentagon that Joe Biden may one day have to fight a war.
Not a small war. A big one. Against China or Russia.
Military and intelligence officials believe China has stepped up its timetable for taking over Taiwan to "within six years," which could force the US to enter a potentially catastrophic conflict in the Pacific.
Meanwhile, Vladimir Putin continues to mass forces on Ukraine’s border, testing Mr Biden’s nerve.
Mr Biden was Vice President when Russia annexed Crimea in 2014. It was kicked out of the G8, but seven years later there has been no reversal.
Mr Putin senses weakness in his American counterpart, and the Kremlin is calculating its next move.
However, it is, for the first time, China that is now considered the most severe threat to US national security.
The issue of Taiwan, in particular, is keeping Pentagon analysts up late at night. They are running war games.
One recent massive simulation showed the US winning a Pyrrhic victory following a Chinese invasion of Taiwan.
China's forces were pinned in one part of the island, but the US sustained heavy losses.
America's Air Force won the day, but only because the simulation employed drone technology that does not actually exist yet.
Two previous simulations had led to devastating defeats for the US with huge numbers of casualties, which officials have refused to put a number on.
For its part China has been upping the ante ever since Mr Biden took office.
In the days immediately after his inauguration Beijing sent two dozen war planes into the Taiwan Strait in a show of force.
Last month, Chinese officials had a public spat with US secretary of state Tony Blinken at a meeting in Alaska.
On Wednesday Christopher Wray, the FBI Director, revealed his agency was opening an investigation linked to the Chinese government, including economic espionage, every 10 hours.
Current Pentagon thinking is that China will double, and potentially quadruple, its nuclear stockpile by 2030.
For decades the US policy toward Taiwan has been one of so-called "strategic ambiguity," committing to helping the democratic island of 24 million people, but without saying how much.
On Capitol Hill, Republicans are becoming increasingly hawkish, demanding a firmer and clearer stance from Mr Biden toward Beijing.
Rick Scott, a Republican senator from Florida, has introduced a bill that would authorise the US president to use military force to protect Taiwan.
Mr Scott said: "We are in a new Cold War with Communist China. I have no faith that President Biden will do what is needed in this critical moment."
Admiral Philip Davidson, the most senior US military commander in the Asia-Pacific region, told a recent Senate hearing the risk of a Chinese military move on Taiwan was rising.
He said: "The threat is manifest during this decade. In fact, in the next six years."
Admiral John Aquilino, his expected successor, added: "This problem is much closer to us than most think.”
Meanwhile, Mr Biden's daily intelligence briefing is also believed to be heavy with details of Russian troop movements.
The number of Russian forces massed on Ukraine’s borders is now the highest since 2014.
This week Ukraine’s defence minister claimed the Kremlin was preparing to potentially store nuclear weapons in Crimea.
Russia's navy has sent warships to conduct target practice in the Black Sea.
And following bellicose rhetoric from Moscow the US decided not to go ahead with plans to deploy two of its own destroyers - believed to be the USS Donald Cook and USS Roosevelt - to the Black Sea.
Mr Putin may interpret that as a further sign of weakness by Mr Biden.
Mr Biden’s own world view is also contributing to the possibility - some would say inevitability - of eventual conflict with either China or Russia.
The US president has made clear he sees the present time as a future-defining moment, a global reckoning between democracy and autocracy.
His personal relationships with the leaders of China and Russia also do not bode well for peace.
Donald Trump had friendly interactions with Xi Jinping and Mr Putin, but Mr Biden has publicly insulted both of them.
Mr Putin was said to have been particularly angered by Mr Biden calling him a “killer” in a TV interview.
When he was Vice President Mr Biden spent many hours with Mr Xi, and says he knows him "pretty well".
But to his mind Mr Xi and Mr Putin are as bad as each other.
"He [Mr Xi] is one of the guys, like Putin, who thinks that autocracy is the wave of the future," Mr Biden said recently.
The US president isn’t the only one seeing this as a pivotal moment in history.
As Tobias Ellwood, the former British defence minister, put it this week: "There is a 1930s feel to the world I think at the moment. We’ve got China doing its thing, Russia very aggressive."
In making their calculations Mr Xi and Mr Putin will bear in mind that Mr Biden’s military decision-making record is not the best.
He supported invading Iraq, but then regretted it.
A decade later he expressed reluctance about proceeding with the raid to kill Osama bin Laden.
This week, he withdrew all US troops from Afghanistan despite warnings it would embolden terrorists.
Whether Mr Biden will have the appetite to counter military advances by Beijing and Moscow remains to be seen.
A future war with China or Russia looms on Joe Biden’s horizon
Tensions are escalating over Taiwan and Ukraine