A P-8A Poseidon surveillance plane conducts flyovers above the Enterprise Carrier Strike Group on February 3, 2012 in this handout photo courtesy of the U.S. Navy. REUTERS/U.S. Navy/Mass Communication Specialist 3rd Class Daniel J. Meshel/Handout

WASHINGTON (Reuters) - The U.S. government has approved the sale of up to nine Boeing Co BA.N P-8A Poseidon maritime patrol planes to Britain in a deal valued at up to $3.2 billion, the U.S. Defense Department said Friday.

The Pentagon’s Defense Security Cooperation Agency (DSCA), which oversees foreign arms sales, notified Congress about the potential sale on Thursday. Lawmakers now have 15 days to block the sale although such action is unlikely given close ties between the United States and the UK.

The proposed sale will enhance Britain’s capabilities to provide national defense and contribute to NATO and coalition operations, DSCA said in a statement. It said the deal was a top priority for Britain.

Britain announced its intention to buy the submarine-hunting patrol planes in November as part of a five-year plan that will increase spending by 12 billion pounds ($16.96 billion) to 178 billion pounds ($251.60 billion) over the next decade.

At the time, British Prime Minister David Cameron said the planes would help the UK protect its nuclear deterrent and fill a gap left by a much-criticized decision to scrap the Nimrod spy-plane program in 2010.

DSCA said Britain had retained core skills in maritime patrol and reconnaissance following the retirement of the Nimrod aircraft through personnel exchange programs that have left UK forces work on the U.S. Navy P-8A aircraft.

Additional contractors on the deal include ViaSat Inc VSAT.O, Rockwell Collins Inc COL.N, Spirit Aerosystems Holdings Inc SPR.N, Raytheon Co RTN.N, Northrop Grumman Corp NOC.N and Harris Corp HRS.N and General Electric Co GE.N, the agency said.