For nearly a decade now, Walt Disney World and Universal have been engaged in an increasingly expensive arms race.

It began in 2010, when Universal opened the $265-million Wizarding World of Harry Potter, which, almost overnight, transformed a struggling, second-tier resort into a true competitor to Disney. Universal, owned by Comcast, has since added new rides based on King Kong, Transformers, The Tonight Show and Despicable Me, along with two new hotels (plus another under construction), and, most important, a second Harry Potter land, built for a reported $400 million and opened in 2014.

Disney, meanwhile, has countered with additions such as a $425-million expansion of the Fantasyland section of its Magic Kingdom theme park. It followed that at Epcot in 2016 with an attraction based on the animated movie Frozen.

The escalation has continued in 2017. But this year, both resorts are focusing their biggest investments on shoring up key vulnerabilities.