The reality is that SoftBank has been all-in on the U.S. for years.
In addition to its majority ownership of wireless carrier Sprint, SoftBank is a fixture in Silicon Valley. Last year, the company led a $1 billion investment in online lender SoFi, calling it a "game changer in the fintech space." In October, SoftBank spearheaded a $130 million financing in Zymergen, a start-up that's combining automation and biology.
According to CB Insights, SoftBank has participated in 13 private company deals since the beginning of 2014, totaling $2 billion. Way back in 1996, SoftBank partnered with Yahoo to form Yahoo Japan.
Son, who founded SoftBank in 1981, visited Trump on Tuesday for a meeting with the incoming president. Trump sent out two tweets immediately following the meeting saying that Masa — as he's known — had committed to investing $50 billion in the U.S.
"Masa said he would never do this had we (Trump) not won the election!" Trump wrote.
In fact, SoftBank, along with Saudi Arabia's sovereign wealth fund, announced plans in October for a technology investment fund that could reach $100 billion in size. The $50 billion Son was referencing is tied to that fund, according to The Wall Street Journal.
Son has been bulking up in U.S. Last year, SoftBank said it would be closing its venture arm SoftBank Capital, which was led by former Google executive Nikesh Arora.
Son was looking to do bigger deals and move away from early-stage investments, so he transferred control of the venture portfolio to New York-based firm Lerer Hippeau Ventures.
"If they're going to put $50 billion to work, writing $500,000 checks into seed rounds is probably not the way to go," said Paul Martino, a partner at venture firm Bullpen Capital, which invested alongside SoftBank Capital in game developer JumpRamp.
That's not to say that Son views a Trump administration as just business as usual.
It's anyone's guess where Trump lands on mega mergers. During the campaign, he voiced opposition to AT&T's effort to acquire Time Warner, claiming it would give the telecommunications giant too much power. But, the CEOs of those companies said recently that they're not concerned.
Should a Sprint deal with T-Mobile come to pass, Son would have every reason to put big money to work building out the network, said Venky Ganesan, a partner at Silicon Valley firm Menlo Ventures.
"I actually think that Sprint under SoftBank is willing to invest in infrastructure in America," said Ganesan. "There is going to be more money coming in that is going to create jobs."
According to Trump's tweets, the aim is to create 50,000 jobs.
That's an ambitious number and represents almost 70 times the number of jobs that are staying in the U.S. following Trump's recent deal with Carrier in Indiana.
For his part, Son is on quite a run, including generating billions of dollars from an early investment in China's Alibaba. Joe Medved, who worked for SoftBank Capital and transferred to Lerer Hippeau last year along with the venture portfolio, saw his former boss in action.
Son "has a 300-year plan for SoftBank," Medved said in an e-mail. He "is one of the world's most inspirational entrepreneurs and investors. His prescience has led to early investments ranging from Yahoo, when the internet emerged in the U.S., to Alibaba, as the web spread across China. Both are major contributors to the enterprise value of SoftBank Group."