(a) The district courts shall have original jurisdiction without regard to amount in controversy of any nonjury civil action against a foreign state as defined in section 1603(a) of this title as to any claim for relief in personam with respect to which the foreign state is not entitled to immunity either under sections 1605-1607 of this title or under any applicable international agreement. (b) Personal jurisdiction over a foreign state shall exist as to every claim for relief over which the district courts have jurisdiction under subsection (a) where service has been made under section 1608 of this title. (c) For purposes of subsection (b), an appearance by a foreign state does not confer personal jurisdiction with respect to any claim for relief not arising out of any transaction or occurrence enumerated in sections 1605-1607 of this title.