McDonald's is preparing for its entry into the spicy chicken sandwich wars.

The fast-food chain is planning to launch a spicy BBQ sandwich in mid-September, according to leaked documents shared with Business Insider in June. The sandwich will be accompanied by spicy BBQ glazed tenders.

"Hold tight, because McDonald's is bringing the heat starting in September," a McDonald's representative said in an email to Business Insider in June.

McDonald's spicy BBQ sandwich and spicy BBQ glazed tenders will launch in mid-September. Business Insider

Both menu items are variations on McDonald's buttermilk crispy chicken, adding a Southwestern sauce to the sandwich and tenders. According to one McDonald's employee, the menu items come after years of customer demands for a spicy chicken sandwich at the chain.

The limited-time offer will come on the heels of a massive chicken sandwich debate.

Last week, Popeyes rolled out a new chicken sandwich, available with or without spice. The sandwich was an immediate hit, inspiring intense debate on whether it could be the best version of the fast-food chicken sandwich available in the US.

Read more: I ate spicy chicken sandwiches from Chick-fil-A, Popeyes, and Wendy's, and Popeyes' was majorly disappointing

Soon, Popeyes, Chick-fil-A, Wendy's, and more were sparring online. Twitter users were quick to take sides in the chicken sandwich throwdown.

Chick-fil-A's and Popeyes' chicken sandwiches. Irene Jiang / Business Insider

If the chicken sandwich debate feels like it came out of nowhere, think again. Chick-fil-A's recent growth is forcing chains across the US to up their chicken sandwich game, with a number of chains doubling down on testing and adding new menu items in recent months.

In addition to Popeyes, Buffalo Wild Wings and Cracker Barrel rolled out new chicken sandwiches in recent months. CNBC reported in July that McDonald's franchisees are pushing the company to make developing a new chicken sandwich the chain's "top priority."

"Chick Fil A's results demonstrate the power of chicken," McDonald's National Owners Association board said in an email obtained by CNBC's Amelia Lucas.

If you're a McDonald's employee or franchisee with a story to share, email ktaylor@businessinsider.com.