Tomas decided to call it a day following a red card against Belgium in the World Cup final qualifying play-offs last year, against which Glenn Roeder spoke out strongly at the time.
And, having informed the Hammers boss not only of his gratitude about that support at the time, but his reasoning behind the change of heart, Glenn reveals: "Tomas will resume playing in the New Year but first he must serve a four match ban for being unfairly sent off against Belgium last year in a World Cup qualifier.
"I was at the game in Brussels, and without doubt the Belgian player made it look a lot worse than it was - I didn't even feel Tomas caught him, and I watched it enough times in slow motion.
"Tomas was upset that he didn't get the support that he felt he deserved from the Czech FA, and I think he decided to bring his international career to an end because of that lack of support.
"But there is a new manager in charge of the Czech Republic, and, as I understand it, he wants Tomas back in the squad when he is free from suspension.
"Tomas has now reviewed the situation and I'm told by him and Ludo that he wants to resume his career, and rightly so, with the Czech Republic after Christmas."
Glenn has four senior centre halves to choose from this season, of whom three - Tomas, Gary Breen, and Christian Dailly - are all internationals.
The fourth, Ian Pearce, was being tipped in some circles to break through into the England squad before his horrendous run of injuries.
Says Glenn: "I expect good competition there next this year but we have to solve our defensive frailties at times."
With the disappointment of the two goals conceded against Charlton in mind, he says: "There is an answer between the four senior centre halves but of course it is not just about them, it is also how we defend in the full back positions and how we defend as a midfield to protect the back four.
"When you concede goals it is not always necessarily about the goalkeeper and the two centre backs - they need protection to be able to do their job properly.
"In fact the two goals we conceded against Charlton had nothing to do with the two centre backs, and you couldn't fault them. It was other players in the team that didn't do their job on the day."