AP ��An Iranian naval exercise involving at least 100 small boats in and around the Strait of Hormuz last week was meant as a message to the U.S. for re-imposing economic sanctions on Tehran, the top U.S. commander in the Middle East said Wednesday.

Gen. Joseph Votel, head of U.S. Central Command, told Pentagon reporters that Iran was showcasing its military capabilities, amid recent threats by Iranian President Hassan Rouhani to close off the strait.

"It's pretty clear to us that they were trying to use that exercise to send a message to us that, as we approach the period for the sanctions here, they had some capabilities," said Votel.

The message back to Iran from U.S. Central Command was, "We are aware of what's going on and we remain ready to protect ourselves," Votel said.

More broadly, Votel condemned Iran for its continued efforts to destabilize other countries in the region, including Syria, Iraq and Yemen.

Iran routinely operates small boats in the Strait of Hormuz and the surrounding area, and has often threatened to shut down the highly traveled waterway. In recent weeks Rouhani renewed the threat, saying that if sanctions threatened Iran's crude oil exports, the rest of the Mideast's exports would be threatened as well.

About a third of all oil traded by sea passes through the Strait of Hormuz.

Votel said Iran has the ability to plant mines and explosive boats in the waterway, as well as use missiles and radar along the coast. But he said the U.S. and allies routinely train for that possibility and are prepared to insure that freedom of navigation and commerce continues in those waters.

U.S. sanctions that had been eased by the Obama administration under the landmark 2015 nuclear deal took effect again Tuesday, following President Donald Trump's decision in May to withdraw from the accord, saying it was too generous. Renewed sanctions targeting Iran's oil industry and banking sector will resume Nov. 4.

Votel said much of this Iranian activity in the strait and in the region is being perpetrated by Gen. Qassem Soleimani, who heads the elite Quds Force of Iran's hard-line paramilitary Revolutionary Guard.

"Wherever you see Iranian activity you see Qassem Soleimani," said Votel, calling the Quds Force the principle threat in the region.

Iran has been active in Syria, backing the government of President Bashar Assad, while also stoking violence in the southern part of the country and triggering military counterattacks from Israel.

Israel has warned Iran against building up a military presence on its doorstep. The U.S. and Saudi Arabia have repeatedly condemned Iran for providing missiles to Yemeni Houthi rebels, who have fired toward Riyadh.