One thing both franchises have in common is Los Angeles.
Since the return, in which they moved into LA Galaxy's home ground, Dignity Health Sports Park, they have struggled to bring in big crowds.
Spanos was responding to a story Monday by The Athletic, which reported the Chargers and the National Football League could look at moving the team to London, partly because of concerns over the Los Angeles market.
The Chargers' official Twitter account also responded to talk of relocation.
The Chargers franchise began in 1960, but only stayed in Los Angeles for a single year before moving to San Diego in 1961.
The NFL staged four games in London this season and has played 28 games in the city since 2007.
They will move to SoFi Stadium in Inglewood next season, which will also be the home of the Los Angeles Rams.
Less than 24 hours later, Chargers owner Dean Spanos was asked about those reports and he did not mince words when firing back.
The report from the Athletic was posted Monday night and, citing NFL sources, noted that "the possibility of the Chargers moving to London has been broached among league personnel".
The Chargers played a game in London once in 2008 and again in 2018. That in turn would likely set in motion a greater divisional realignment to which other teams would have to agree.
A United Kingdom move could still be on the cards, but for the Jacksonville Jaguars instead. The Jaguars play in the unsexy market of Jacksonville and they've been playing a game in the United Kingdom annually since 2013. "We're seeing progress every day, and we look forward to building on that".