Weselsky said only that he would "announce [the strike] in good time" - although his conception of sufficient notice proved unpopular in November, when he gave less than 24 hours' warning of a days-long strike action.
In recent days GDL have threatened to go ahead with a strike lasting more than 100 hours, something they pulled out of halfway through during their last industrial action in November.
"We are in no mood to hold up the gun and say 'now or never' and then simply watch moss grow over the path just beacuse DB continues to invite us to the negotiating table," Weselsky told reporters earlier on Wednesday, his 56th birthday.
On Tuesday, Deutsche Bahn (DB) refused to sign a nine point document that outlined what GDL thought still had to be negotiated upon.
"We could not sign it the way it is," DB's head of human resources Ulrich Weber told Spiegel in an interview published on Wednesday.
Weber said the document did not reflect the current state of negotiations, but was a restatement of GDL's original demands from the beginning of the bargaining process.
"It sounds like a formal move at first, but it's not. GDL is doing this because they want to split our workforce," Weber said, adding that DB had countered GDL's offer with a "constructive proposal".
This is the seventh industrial action called in the ongoing dispute between GDL and its employers.
At stake is a work week reduced from 39 hours to 37 hours and a five percent increase in wages, but Dr. Stefan Heinz at the Free University in Berlin told The Local the conflict goes much deeper than that.
"The GDL is feeling threatened by these [planned] new labour laws that limit strike rights and they are showing their strength. They are a small union of specialised workers who can strike very effectively," he said in an interview with The Local.
Heinz is referring to the incoming united collective bargaining law (Einheitstarifgesetz) that will only give bargaining powers to the union with the most members working for an employer.
This is the case with DB, which is negotiating with GDL as well as the EVG, a union that represents all other DB workers. EVG represents 17,000 DB employees while GDL counts 34,000 members. However, EVG is an umbrella union that represents 209,000 workers.
"The GDL does not want the EVG negotiating on their behalf and would rather have it the other way around," Heinz said. "The EVG have to agree to that, but they also know that the GDL can strike much more effectively than their employees – they are a specialised work force – whereas if EVG employees, such as the on-board restaurant staff were to strike, people would just get a sandwich before they get on the train.
"No-one would take a strike like that seriously as long as they can get to where they are going."
The EVG also "heartily greeted" the new labour law when it was announced, said Heinz.
DB did agree to let the GDL negotiate on behalf of both unions in December, but Weber said there is now the question of how the collective agreements will be negotiated between the unions.
"We feel a solution is in reach," Weber said.
But Heinz said that this is just part of Weber's usual tactic.
"He always says that they are speaking, negotiatioing and listening to the GDL, but here we are, still arguing over the same thing since last fall," Heinz said.
In his interview with Spiegel, Weber confirmed that the industrial action had so far cost DB, which is still partly state-owned and -operated, €150 million.
Negotiations with EVG are ongoing and "moving forward", said Weber.
SEE ALSO: The man who stopped Germany's trains