WASHINGTON: The Obama adminstration is consulting Congress on an unusual proposal to transfer U.S. Marine Corps attack helicopters to Turkey, U.S. officials said Thursday, as Ankara tries to exact revenge for a major attack by Kurdish separatists.

Turkey, a NATO ally, has been seeking AH-1 SuperCobra helicopters to replace those lost in its long struggle against separatist rebels.

Under the administration’s plan, the Marines would get two new, late-model Textron Inc Bell AH-1Z SuperCobras in exchange for the three AH-1W aircraft that would be transferred to Ankara from current inventory, a congressional official said.

The officials declined to be identified because of the matter’s sensitivity and because they were not authorized to speak on the record. The idea to take weapons from the U.S. arsenal was rare, they said.

The proposal has been held up amid lawmakers’ questions about increasingly distant relations between Muslim-majority Turkey and Israel.

The AH-1W has sold previously for about $10 million. Turkey bought 10 of them in the 1990s. The larger, twin-engine AH-IZ may sell for about $30 million, according to industry sources.

Under the U.S. Arms Export Control Act, the executive branch must provide 15 days’ notice to Congress before going ahead with significant arms transfers to a NATO partner.