With the approval of the Secretary, any contract or research authorized by
section 7303 of this title, the performance of which involves a risk of an unusually hazardous nature, may provide that the United States will indemnify the contractor as provided in paragraph (2), but only to the extent that the liability, loss, or damage concerned arises out of the direct performance of the contract and to the extent not covered by the financial protection required under subsection (e).