Local sources have reported that Iran recently sent soldiers and a large number of long-range and ballistic missiles. The military basing came after Iran signed an accord with Eritrea to revamp the Russian-built refinery used by the Eritrean Oil Company, also known as Assab Oil Company.
Iran can interfere with Gulf oil leaving through the Strait of Hormuz already. And now the pipelines to the Red Sea that bypass Hormuz can be hit by Iranian forces in Eritrea. Add the Iranian presence in southern Lebanon and Gaza where they might launch strikes on the Suez Canal (with a Mumbai like assault or longer-ranged missiles if they can get those into the region) completes the ring.
This continues the trend that really started in earnest in the 1980s during the Iran-Iraq War as the Arab oil producers sought to put their oil exporting capacity beyond the reach of Iran's military power. Oil pipelines to the Red Sea avoided Iranian naval assets in the Persian Gulf. So Iran has gone to the Red Sea.
The article draws dramatic conclusions from the Iranian deployment to Eritrea:
With the addition of a new naval base at Jask at the mouth of the Strait of Hormuz, and new basing at Assab in Eritrea, Iran can exercise a decisive military presence on multiple shores astride the pivotal oil sea lanes.
Decisive? Hardly. If we use our military might, Iranian forces would have a short but exciting life. To succeed, Iran requires us to be pretty passive in the face of their easily defeated forces.
They're wrong to assume our passivity, right?
UPDATE: Simon M. wrote that the source for the report on Iranian deployments to Eritrea come from a less than reliable government opposition group. Count this report as questionable until verified by better sources. Still, the idea that Iran might try to continue their 1980s efforts to interdict Gulf oil exports is valid, I believe. I wouldn't be shocked if they eventually try this. Although if they do, don't panic. The Iranians are violent and crazed but without nukes they just aren't very powerful.