Australia says it has signed an order for eight Boeing P-8A maritime patrol aircraft and has taken an option for four more of the Renton-built planes.
That initial order is worth about $3.6 billion, said the Australian government.
The P-8A is based on Boeing's popular 737 twin-engine airliner. Boeing builds all of its 737s and P-8As at its plant in Renton.
Both the U.S. Navy and India have ordered versions of the 737-based plane.
The task of that plane is to patrol the oceans looking for submarines and surface warships. In the U.S. Navy version, the plane carries weapons designed to sink those submarines.
What is the passenger compartment in a regular 737 is filled with electronic detection and communications gear in the P-8A.
The P-8A is replacing the aging P3 Orion four-engine turboprop aircraft in the inventory of the U.S. and Australian navies.
Boeing expects that Australia and India won't be the only foreign nations to order the P-8A as existing maritime patrol aircraft age and become outdated.
The first of the patrol craft built for Australia is scheduled to be delivered in 2017.