Lockheed Martin has won a second multimillion-dollar Air Force contract to design a hypersonic weapon prototype, as the U.S. tries to match Russia and China in hypersonic development.

The award, which is "not-to-exceed" $480 million, comes four months after the Bethesda, Maryland-based defense giant won its first hypersonic weapons contract. Development will take place in Orlando, Florida, under Lockheed's missiles and fire control unit and is expected to be completed by November 2021.

The Pentagon unveiled the deal Monday.

A hypersonic weapon is a missile that travels at Mach 5 or higher, which is at least five times faster than the speed of sound. That means a hypersonic weapon can travel about one mile per second.

The Pentagon's second hypersonic contract comes as Russia and China sprint to add these emerging weapons to their arsenals.

Read more: Russia and China are 'aggressively developing' hypersonic weapons — here's what they are and why the US can't defend against them

Earlier this year, Russian President Vladimir Putin boasted about nuclear and hypersonic weapons, which he described as "invincible" during a state of the nation address. Of the six weapons Putin debuted in March, CNBC has learned that two of them will be ready for war by 2020, according to sources with direct knowledge of U.S. intelligence reports.

Currently, the Pentagon has nearly a dozen programs tasked with developing and defending against the new breed of weapons.

In April, Lockheed Martin secured a $928 million contract to build an undefined number of hypersonic conventional strike weapons. According to the contract, the defense giant will be responsible for designing, engineering, weapon integration and logistical support. The development will take place in Huntsville, Alabama, which is known as "Rocket City" as it was the birthplace of America's rocket program.

Lockheed Martin is also in the process of developing the SR-72, a hypersonic unmanned plane dubbed the "son of the Blackbird." In 2014, the defense giant was awarded $892,292 by NASA to study the development of the hypersonic spy plane.