The US has suspend the participation of its ally Turkey in the F-35 stealth fighter jet programme after Ankara decided to buy Russian S-400 air defence system.
The US has expressed its concern as Turkey is an ally of the North Atlantic Treaty Organisation, the alliance formed to counter the Soviet Union.
Turkey's Foreign Minster Mevlut Cavusoglu met his Russian counterpart Sergei Lavrov last week, giving a go ahead to the S-400 purchase.
The United States has been clear that Turkey's acquisition of the S-400 is unacceptable, said Acting Chief Pentagon Spokesperson Charles Summers Jr.
Should Turkey procure the S-400, their continued participation in the F-35 program is at risk," Summers said.
Regretting the situation facing US-Turkey partnership in the F-35 programme, Summers said the Department of Defense is taking prudent steps to protect the shared investments made in this critical technology and ensure resiliency of the F-35 supply chain.
He said that secondary sources of supply for Turkish-produced parts are now in development.
Our important dialogue on this matter will continue, however, until they forgo delivery of the S-400, the United States has suspended deliveries and activities associated with the stand-up of Turkey's F-35 operational capability, he said.
Turkey-based companies manufacture parts for all F-35 variants and customers. The plane's manufacturer, Lockheed Martin, said that contracts with Turkish companies to build F-35 parts had been expected to reach USD 12 billion, media reports said.
The development gains importance because India too has decided to buy the S-400 system from Russia. The S-400 is known as Russia's most advanced long-range surface-to-air missile defence system.
However, in recent weeks, US officials have said that India and Turkey cannot be compared even if both of them are buying S-400 from Russia.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)