America¡¯s biggest supermarket chain is seeing signs that U.S. shoppers are getting nervous about the future.

¡°It¡¯s fascinating right now from a customer standpoint. They feel incredibly good about the economy but very nervous about where things are headed,¡± Kroger Co. Chief Executive Officer Rodney McMullen said in an onstage interview at the National Retail Federation¡¯s annual trade show in New York City.

¡°If you talk about questions in the present,¡± American shoppers feel just fine, but ¡°if you change the question a little to ¡®where do you think things are going,¡¯ there¡¯s a lot of uncertainty,¡± he said.

Kroger operates supermarkets and other types of stores in about 35 states plus the District of Columbia under various banners, giving the Cincinnati-based company a clear window into Americans¡¯ buying habits.

McMullen¡¯s observations come at a time when the consumer environment in the U.S. is the strongest in years, with low gas prices and rising median wages fueling consumer confidence.

But cracks have started to emerge: retailers¡¯ in-store traffic slipped during the critical Black Friday weekend in November, and a series of lackluster holiday sales reports in the past week suggest consumer optimism may not be as high as forecasters expected heading into the Christmas season.

McMullen said he isn¡¯t yet bracing for the worst, and executives at Kroger ¡°don¡¯t see anything that would cause us to say there¡¯s a recession right around the corner.¡±

Still, the U.S. appears to be at a ¡°fork in the road,¡± and if wider macroeconomic issues like trade negotiations don¡¯t get resolved, the situation could take a turn for the worse, he said.

¡°It¡¯s easy to paint a picture where things could be fabulous¡± and another ¡°where things could be a recession,¡± McMullen said. ¡°If those things don¡¯t play out the way we all want it to, then I think a recession is something that could happen.¡±