For the purposes of
section 1110 of this title, and subject to
section 1113 of this title, a disease covered by
section 1116 of this title becoming manifest as specified in that section in a veteran who, during active military, naval, or air service, served offshore of the Republic of Vietnam during the period beginning on
January 9, 1962, and ending on
May 7, 1975, shall be considered to have been incurred in or aggravated by such service, notwithstanding that there is no record of evidence of such disease during the period of such service.