I noted the possibility that Iran's Eritrea links were an effort to extend Iran's reach to this new route for oil exports.
Strategypage notes the Iranian-Eritrean ties and the oil implications:
Several years ago Eritrea began developing a strategic relationship with Iran. As both nations have become more isolated, that relationship has strengthened. Iran can already close the Strait of Hormuz (temporarily, with mines). Eritrea sits on the Bab al Mandab (Gate of Tears), the strait between the Indian Ocean and the Red Sea. This is a major route for international shipping traffic (to and from the Suez Canal).
And the region is an alternate oil export route for Saudi Arabia, which I consider far more significant than the shipping traffic angle. Oil is what drives Iran to embrace Eritrea.
If Iran can get away with it, they'll put miltiary assets that can target oil tankers into Eritrea.