By Arunima Banerjee
(Reuters) - U.S. defense contractor Northrop Grumman Corp <NOC.N> said on Monday it would buy Orbital ATK Inc <OA.N> for about $7.8 billion in a deal that gives it greater access to lucrative government contracts and expands its arsenal of missile defense systems and space rockets.
The all-cash transaction is the biggest in the defense sector in two years and comes as North Korea's missile and nuclear weapons threats grow, heightening tensions with the United States and its allies.
- PHOTOS: New art and old relics at Mickey Mouse's NYC gallery 25 Pictures
- PHOTOS: See Yes on 3 supporters react to historic transgender rights Question 3 win 11 Pictures
- PHOTOS: A look back at Queen performing in the 1970s and 1980s 22 Pictures
- All of these celebrities have had their nudes leaked 35 Pictures
- PHOTOS: A look at Idris Elba's style through the years 20 Pictures
- PHOTOS: Heidi Klum's annual Halloween party and other amazing celebrity costumes 17 Pictures
- These are the spookiest cities per capita in the U.S. 5 Pictures
- Food Network star talks pumpkin carving 1 Pictures
- Who is Alexander Edwards, Amber Rose's new boyfriend? 9 Pictures
- Is Cardi B pregnant again? This tweet has people guessing 6 Pictures
- Natural Museum's best wildlife photos of the year 5 Pictures
"Clearly, as we watch what's happening around our globe, the rather rapid advance of some of our potential adversaries is quite concerning," Northrop Chief Executive Wes Bush said on a call with analysts.
Although Northrop already has a significant presence in payloads, it has not had launcher capability, an area that Orbital brings for both space and missile defense, Vertical Research Partners analyst Robert Stallard said on Monday.
Orbital has contracts with NASA and the U.S. Army. The Dulles, Virginia-based company is one of the two firms hired by NASA to fly cargo to the International Space Station under an initial contract worth up to $3.1 billion.
Northrop's purchase of Orbital would help sharpen its focus on small space systems, launch vehicles, missiles and munitions.
The deal also comes ahead of planned upgrades of U.S. ballistic systems, which are expected to drive demand for missiles, potentially benefiting companies such as Northrop.
Shares of Aerojet Rocketdyne <AJRD.N>, a direct competitor with Orbital ATK in several space and missile businesses, rose 6.7 percent to $30.24, as the higher valuation for Orbital boosted Aerojet shares.
The U.S. Air Force has called for proposals to replace its aging nuclear missiles and intercontinental ballistic missile system as the military moves ahead with a costly modernization of its atomic weapons.
Falls Church, Virginia-based Northrop's other businesses, such as aerospace and mission systems and technology services, provide aircraft, electronic warfare systems and network defense services.
"Given that Northrop already operates in the space field, it is possible that there could be some overlapping activity or increased vertical integration that could prompt regulatory scrutiny," Stallard said.
Northrop's offer price of $134.50 per Orbital share represents a premium of 22 percent over the stock's Friday close. Orbital's shares gained 20 percent to $132.25 on Monday, while Northrop's stock rose 3.3 percent.
Northrop will assume $1.4 billion of Orbital's net debt and expects to close the deal in the first half of 2018.
Northrop's last acquisition spree more than a decade ago included its 2002 purchase of TRW Inc for about $7.8 billion.
Mergers of U.S. aerospace and defense firms has totaled $40.5 billion so far in 2017, the strongest year-to-date performance of all time for dealmaking in the industry, according to Thomson Reuters data.
Perella Weinberg is the financial adviser to Northrop, while Citigroup is advising Orbital.
Earlier this month, United Technologies <UTX.N> agreed to buy avionics and interiors maker Rockwell Collins <COL.N> in a $30-billion deal.
(Reporting by Arunima Banerjee and Supantha Mukherjee in Bengaluru; Editing by Sai Sachin Ravikumar and Nick Zieminski)