If you want to buy the new Blu-ray of Star Wars: The Last Jedi from Amazon, you’d better be an Amazon Prime member. The online behemoth seems to be flexing its muscles a bit, leveraging the most popular movie of 2017 in an effort to sell more Prime subscriptions.

Slate notes that the discrepancy began a few weeks ago, when the latest Star Wars movie first became available for presale. When the home version of the movie was released on March 27, the Blu-ray disc was listed as “out of stock,” although the streaming version was available through Amazon, and many other online retailers had discs for sale.

Currently, the Blu-ray, DVD, and 4K Ultra HD versions are all listed as “Exclusively for Prime Members” at Amazon’s site.

It certainly doesn’t seem to be hurting sales, as The Last Jedi currently occupies the #2 and #5 spots on Amazon’s best-selling list. It is a minor annoyance for people who aren’t Prime members, however, and it extends to other popular franchises as well. Marvel movies are also unavailable unless you’re a Prime member, although the streaming Prime Video versions are available to anyone.

Aside from an effort to boost Prime subscriptions (the “Free Trial” offer is prominently featured for non-members when trying to order the disc), this kerfuffle is likely the latest salvo in the ongoing battle between Amazon and Disney. Several years ago, Amazon halted pre-orders for several Disney DVDs, including Maleficent and Captain America: Winter Soldier.

After scooping up the 21st Century Fox properties in a multi-billion-dollar deal, Disney has already announced plans for its own comprehensive streaming service to compete directly with providers like Amazon Prime. Disney CEO Bob Iger has also said the company will be pulling all Star Wars and Marvel films from Netflix in 2019.

The Last Jedi disc copies and the streaming version are both loaded with extras, but one of the most interesting is a “silent” version that doesn’t include any dialogue or effects — the only audio is John Williams’ iconic score. Of course, there’s a catch. To watch it, you need to sign up for the Movies Anywhere app, the Disney-backed digital movie aggregator.

Amazon recently revealed that it has 100 million Prime subscribers, but the Disney-Fox merger means that the Mighty Mouse will now control more than 40 percent of the theatrical movie market, according to Deadline. Unfortunately, this Cold War won’t be resolved anytime soon, and could well result in fewer choices and higher prices for consumers.