Citing a Vermont law requiring food manufacturers to put a GMO label on their products, General Mills Inc announced it would place labels on US products containing genetically engineered ingredients, according to a Reuters article by Lisa Baertlein posted at YahooNews.

In general, the U.S. food industry has been averse in the mandatory GMO labeling efforts and has reportedly spent millions of dollars on both state and federal levels. Just recently, the U.S. Senate was able to block a bill (voting 48-49) that would have nullified local and state laws requiring food companies of the labels and would have been a win for the food industry since it would have been up to the companies' discretion whether or not to label their products.

Apparently, General Mills' decision stems from Vermont's newly enacted law requiring the labeling of GMO-containing products. General Mills Chief Operating Officer Jeff Harmening wrote on the company's blog, "Vermont state law requires us to start labeling certain grocery store food packages that contain GMO ingredients or face significant fines. We can't label our products for only one state without significantly driving up costs for our consumers and we simply will not do that."

Vermont is the first state to make the labeling of GMO contents mandatory which would take effect on July 1 according to another YahooNews article by Lisa Rathke.

According to an Eater article by Daniela Galarza, there are two contradicting laws regarding GMO labeling. There is that Vermont labeling law which is scheduled to take effect by July this year and there was that anti-GMO labeling law which would have pre-empted any state law requiring GMO labeling. Fortunately for the pro-GMO labeling faction, the anti-GMO labeling law was blocked by a slim 49 versus 48 votation.  

General Mills said they can't just label their products for a single state. For this reason, they just have to label all U.S. marketed products containing GMO ingredients as such.