The Pentagon has notified Congress of a planned sale to Saudi Arabia of as many as fourLittoral Combat Ships made by Lockheed Martin Corp. for $11.25 billion, as the U.S. works to bolster defenses of its Gulf allies after the nuclear deal with Iran.

The State Department approved the sale under the Foreign Military Sales program, according to a statement Tuesday on the website of the Defense Security Cooperation Agency. The approval allows the Saudis to negotiate contracts for the ships unless Congress passes legislation to block the deal.

The ships are part of a planned modernization, replacing older U.S.-built vessels in the Royal Saudi Navy’s Eastern Fleet. The sale also begins to deliver on President Barack Obama’s pledge to improve the military capabilities of the U.S.’s Arab allies. Saudi Arabia and other nations in the Gulf Cooperation Council sought such reassurances before acquiescing to the U.S.-led deal with Iran on its nuclear program.

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