ALBANY, N.Y. — American athletes in Sochi are facing breakfast without their team-sponsoring Greek yogurt, thanks to a bureaucratic web of international trade negotiations.

Team USA sponsor Chobani, which is based in upstate New York, says it has 5,000 cups of Greek yogurt sitting in a refrigerated warehouse waiting to be flown to the Olympic village. But Russian authorities say the U.S. Department of Agriculture has refused to provide a certificate that is required for dairy products under its customs rules.

U.S. Sen. Charles Schumer, a New York Democrat and a big booster of the state’s burgeoning Greek yogurt industry, this week implored the Russians to snip the red tape and let the shipment through. He said export trade rules should have nothing to do with it, since the yogurt isn’t for sale and is to be eaten only by U.S. citizens in Sochi.

As of Thursday, the situation remained at an impasse.

The Russian Federal Service for Veterinary and Phytosanitary Surveillance put out a statement saying U.S. authorities had failed to provide a required veterinary certificate.

Schumer’s office said the certificate required a statement that no cattle in the U.S. have any of a long list of diseases, which he said would be impossible to say. None of the diseases is related to food safety, a Schumer aide said.

A USDA spokeswoman said the agency is trying to work out an acceptable solution to allow the Chobani shipment.

On Wednesday, Chobani became the third U.S. Olympic Committee sponsor to explicitly condemn Russia’s so-called anti-gay law this week. “It’s disappointing that in 2014 this is still an issue,” said Chobani’s CEO, Hamdi Ulukaya.

Chobani, the No. 1 Greek yogurt brand in the U.S., faces intense competition from French-based Danone, the largest yogurt maker in the world. Chobani ratcheted up the competition with Danone’s Dannon Oikos brand with dueling Super Bowl ads.