Walmart is reportedly asking for-hire drivers and contract trucking companies to quit shipping goods for Amazon if they want to keep their business.

At the recent SMC3 supply chain and logistics conference, industry analyst Satish Jindel told the crowd that Walmart has been warning carriers that they may sever business relationships with companies that also ship for Amazon.

Jindel explained that the “cold war” between the retail titans will force carriers to choose one company or the other.

Walmart has refused to publicly comment on the claim.

“A Wal-Mart spokesman would not disclose the extent of the company’s outside carrier relationships,” the DC Velocity reported.

If Jindel’s claims are true, it wouldn’t be Walmart’s first aggressive anti-Amazon stance, as they recently requested tech partners to quit using Amazon web software, the Wall Street Journal reported.

Freight and logistics analyst Amit Mehrotra said Walmart’s demands “are likely to have significant implications for U.S. transportation companies, in our view, as Amazon and Walmart remain two of the largest users of truckload capacity.”