The motivations for such a ban are not clear, as official documents on from the time are unavailable, but Subandrio's announcement was in line with government policy on passage through Indonesian waters, which was moving towards cracking down on unauthorized passages after an American carrier group had made the voyage earlier in the month.
Penyebab larangan tersebut tidak jelas, karena dokumen-dokumen resmi dari waktu itu tidak tersedia, tetapi pengumuman Subandrio ini sejalan dengan kebijakan pemerintah soal pas melalui perairan Indonesia, menuju penindakan kegiatan-kegiatan ilegal setelah grup kapal induk Amerika lewat di awal bulan.