The Teamsters union announced a strike against Amazon on Thursday morning, with workers picketing in four states. According to them, this is the largest strike against the delivery giant in history.

The strike comes just a week before Christmas, amid the rush of last-minute Christmas gift deliveries.

The strike began at 6 a.m. ET with workers from a plant in New York City, a plant in Atlanta, three in Southern California, one in San Francisco and one in Skokie, Illinois, which is just outside Chicago.

The Teamsters said in a news release that the work stoppage came after Amazon “ignored” a Dec. 15 deadline set by the union to come to the bargaining table.

“If your package is delayed during the holidays, you can blame Amazon’s insatiable greed. We have given Amazon a clear deadline to come to the table and do the right thing for our members. They ignored it,” Teamsters general president Sean M. O’Brien said in a statement.

“These greedy executives have had every chance to show decency and respect for the people who make their obscene profits possible. Instead, they have pushed workers to their limits and are now paying the price. This strike is on them,” he added.

Amazon denies Teamster’s claims.

“For more than a year, the Teamsters have intentionally misled the public by claiming that they represent ‘thousands of Amazon employees and drivers.'” They do not, and this is another attempt to spread a false narrative “said Amazon spokeswoman Kelly Nantel.

Nantel added that the Teamsters allegedly attempted to threaten and force Amazon employees and third-party drivers to join them, “which is illegal and the subject of multiple pending unfair labor practice charges against the union.”

Amazon said its employees have the choice to join a union if they wish, and that the company already offers competitive wages, health benefits and growth opportunities – all items that many unions are demanding.

The Teamsters said nearly 10,0000 Amazon workers have joined the union. That’s just a small fraction of the 1.5 million people employed by the $2 trillion shipping empire.