The United States international has been regularly linked with a move to Liverpool FC since Jurgen Klopp took over the reins in October 2015.
The Reds boss was in charge of Borussia Dortmund when the American forward completed a move to the German club as a youth player.
Pulisic produced his best form under Klopp’s predecessor Thomas Tuchel before the German coach stood down at the end of the 2016-17 term.
He has 24 months left to run on his current deal with the Bundesliga giants and the American isn’t expected to sign a new deal.
Liverpool FC haven’t filled Philippe Coutinho’s void with a world class talent despite the addition of Stoke and Swiss playmaker Xherdan Shaqiri.
Chelsea FC and Manchester United have also been linked with a potential swoop to sign the Dortmund star in recent seasons.
However, Sunday Times reporter Castles believes Pulisic’s most likely next destination is Bayern Munich.
“We could see a transfer this window,” Castles told the Transfer Window podcast.
“He is a player of interest to all the top clubs in England. He has massive additional commercial appeal.
“Liverpool have bid for the player several years ago. They won’t bid this summer. Chelsea have had a look at him if Hazard or Willian were to leave.
“The most likely destination for him his Bayern Munich. I heard Vidal was sold to raise funds to sign Pulisic. They have been working on a deal for some time.”
Pulisic produced his best performances in a Dortmund shirt under Klopp’s successor Thomas Tuchel.
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