The world’s largest defense contractor just got a whole lot bigger.

Lockheed Martin closed its $9 billion acquisition of Sikorsky Helicopter from United Technologies on Friday. The purchase is a bold bet by Lockheed Martin CEO Marillyn Hewson that military spending will pick up after years of shrinking defense budgets. Speaking with Fortune’s Susie Gharib, Hewson talks about why Lockheed made this historic move—its biggest acquisition since the company bought Martin Marietta 20 years ago.

With Sikorsky, the maker of Black Hawk helicopters, Lockheed will now be the world’s largest maker of military helicopters. The acquisition also expands Lockheed’s portfolio, reducing its reliance on the F-35 Joint Strike Fighter, which currently accounts for nearly a quarter of the company’s sales.