The U.S. State Department approved the sale of 20 High Mobility Artillery Rocket System (HIMARS) launchers to Poland to strengthen security in the region and modernize the country's military, the U.S. Defense Security Cooperation Agency said.
Poland asked to buy the HIMARS system, produced by Lockheed Martin, last year.
The DSCA leads U.S. efforts to train and equip allies.
Poland's Defense Minister Mariusz Blaszczak signed off on a new program to update the country's military on Wednesday, including strengthened cyber-security and new air defense and long-range missile systems.
The purchase of the HIMARS launchers and related equipment, estimated to cost around $655 million, is part of this upgrade. "This is a big step towards finalizing this breakthrough contract for the Polish army," Blaszczak tweeted on Friday.
Poland's armed forces have suffered from decades of under-investment and some two-thirds of their equipment dates from the Soviet era.
In a meeting with U.S. President Donald Trump in September, Poland's President Andrzej Duda said Poland was ready to invest $2 billion to facilitate the development of a permanent base.
Duda also said he wants government plans to increase defense spending to 2.5 percent of GDP by 2030 to be speeded up to 2024 if the economy permits.
NATO has requested member countries spend at least 2 percent of their GDP on defense.