service performed in the employ of an instrumentality wholly owned by a foreign government—

(A) if the service is of a character similar to that performed in foreign countries by employees of the United States Government or of an instrumentality thereof; and

(B) if the Secretary of State shall certify to the Secretary of the Treasury that the foreign government, with respect to whose instrumentality and employees thereof exemption is claimed, grants an equivalent exemption with respect to similar service performed in the foreign country by employees of the United States Government and of instrumentalities thereof;