Oil that has washed ashore on several southern Japanese islands is likely from an Iranian tanker that sank in the East China Sea last month, Japan’s coast guard said Friday.
S Oil どんな→[that]
V [has washed]
O ashore どんな→[on] (several southern Japanese) islands
(likely) [from] (an Iranian) tanker
[in] the East China Sea (last month),
S Japan’s coast guard
V [said] (Friday.)