Starbucks and the union organising its workers sued each other Wednesday in a standoff sparked by a social media post over the Israel-Hamas war.

Starbucks sued Workers United in federal court in Iowa Wednesday, saying a pro-Palestinian social media post from a union account early in the Israel-Hamas war angered hundreds of customers and damaged its reputation.

Starbucks is suing for trademark infringement, demanding that Workers United stop using the name “Starbucks Workers United” for the group that is organising the coffee company’s workers. Starbucks also wants the group to stop using a circular green logo that resembles Starbucks’ logo.

Workers United responded with its own filing, asking a federal court in Pennsylvania to rule that it can continue to use Starbucks’ name and a similar logo. Workers United also said Starbucks defamed the union by implying that it supports terrorism and violence.

On October 9, two days after Hamas militants rampaged across communities in southern Israel, Starbucks Workers United posted “Solidarity with Palestine!” on X, formerly known as Twitter. Workers United — a Philadelphia-based affiliate of the Service Employees International Union — said in its lawsuit that workers put up the tweet without the authorisation of union leaders. The post was up for about 40 minutes before it was deleted.

But posts and retweets from local Starbucks Workers United branches supporting Palestinians and condemning Israel were still visible on X Wednesday. Seattle-based Starbucks filed its lawsuit in US District Court for the Southern District of Iowa, noting that Iowa City Starbucks Workers United was among those posting pro-Palestinian messages.

In a letter sent to Workers United on October 13, Starbucks demanded that the union stop using its name and similar logo. In its response, Workers United said Starbucks Workers United’s page on X clearly identifies it as a union.

“Starbucks is seeking to exploit the ongoing tragedy in the Middle East to bolster the company’s anti-union campaign,” Workers United President Lynne Fox wrote in a letter to Starbucks.

In its lawsuit, Workers United noted that unions often use the company name of the workers they represent, including the Amazon Labour Union and the National Football League Players Association.

Starbucks said it received more than 1,000 complaints about the union’s post. The Seattle-based coffee giant said workers had to face hostile customers and received threatening phone calls. Vandals spray-painted Stars of David and a swastika on the windows of a Rhode Island store.

Some lawmakers, including Republican Senator Rick Scott of Florida, called for boycotts of Starbucks.

“If you go to Starbucks, you are supporting killing Jews,” Florida state Rep. Randy Fine, a Republican, tweeted on October 11.