Anaheim, Calif. — The empire is striking back.

While insisting they pay little attention to each other, America’s two largest theme park operators, Disney and Universal, have lately been locked in what certainly seems like an arms race. Universal kicked it off in 2010 with a “Harry Potter” mega-expansion. Disney then introduced or announced new “Cars,” “Avatar” and Fantasyland attractions. Universal, which is owned by Comcast, has since upped the ante, spending billions on new rides and resort hotels.

Now, Disney is rolling out the heavy artillery: After a few years of aggressive investment in overseas theme parks, principally the $5.5 billion Shanghai Disneyland — leaving an opening in the United States for Universal — Disney on Saturday announced expensive “Star Wars”-themed expansions at its California and Florida resorts.

The pair of “Star Wars” lands, each 14 acres, will be built at Disneyland here and at Disney’s Hollywood Studios, a down-on-its-luck park that is part of Walt Disney World in Orlando, Florida. Hollywood Studios will also get a new “Star Wars”-themed weekend fireworks show and 11 acres of new “Toy Story” rides.

Estimated by analysts to cost more than $2 billion, including parking and other infrastructure upgrades, the vast bicoastal expansion — Robert A. Iger, Disney’s chief executive, described the “Star Wars” plans as “jaw-dropping” — marks a long-expected effort by Disney to use its parks to capitalize on its 2012 purchase of Lucasfilm.

Disney has long dismissed Universal as a challenger. But the bold building plans were, in part, read by analysts as a competitive response to Comcast, which is pouring billions of dollars into its own California and Florida properties, in particular focusing on wildly popular “Harry Potter”-themed attractions.

The movie-focused Hollywood Studios, which in some ways started the Disney-Universal rivalry when it opened in 1989, has been especially at risk from Universal’s surge. Hollywood Studios attracted 10.3 million visitors in 2014, just a 2 percent increase from the previous year, making it the least visited of Disney’s four major parks in Orlando. Nearby Universal Studios handled 8.3 million guests, but that was a 17 percent increase from the year before.

“It’s hard for us to recommend spending $80-$100 on a park that has so little to offer,” the new edition of “The Unofficial Guide to Walt Disney World” says of Hollywood Studios, calling a trip to the movie-themed Universal “the superior choice.”

Disney had no comment on competition with Universal.

Robert Niles, editor of the news site Theme Park Insider, said that Disney’s announcement should be interpreted as a response to competition in a broad sense. “Sure, they are looking at Potter, but they are also looking at anything that can compete with a Disney vacation,” he said. “They have to create not just a desire to go see, but a passion to go see.”

Disney’s theme parks unit, a $15.1 billion annual business that is scrutinized as a consumer confidence bellwether, tends to open new attractions four to six years after announcing them. Disney declined to comment on the timing or anticipated construction costs related to its “Star Wars” announcements.