US officials said on Thursday that the United States believes Iran has started carrying out naval exercises in the Arabian Gulf, apparently moving up the timing of annual drills amid heightened tensions with Washington. A US official, speaking on condition of anonymity, told Reuters that possibly more than 100 vessels were involved in the drills, including small boats. A second official expected the drill could be wrapped up this week. The US military’s Central Command confirmed that it has seen an increase in Iranian activity, including in the Strait of Hormuz, a strategic waterway for oil shipments that Iran’s Revolutionary Guards have threatened to block. “We are aware of the increase in Iranian naval operations within the Arabian Gulf, Strait of Hormuz and Gulf of Oman,” said Navy Captain Bill Urban, the chief spokesman at Central Command, which oversees US forces in the Middle East. Meanwhile, Abdul Latif Al Sayadi, a researcher at the National Archives of the UAE Ministry of Presidential Affairs said Irans potential closure of the Strait of Hormuz would violate the United Nations Convention on the Law of the Sea of December 1982, which ensures the right of transit for all countries, even within the territorial waters of other countries. Al Sayadi was speaking during a lecture held Wednesday by the Emirates Center for Strategic Studies and Research, ECSSR, titled, "Iran’s Threats to Close the Hormuz Strait from an International Law Perspective." Al Sayadi explained that the potential closure would be "an attack on the sovereignty of several countries, whose maritime borders fall within the area that Iran threatens to shut down.” The expert also explained that Iran cannot close the Strait because its ports are located inside the basin of the Arabian Gulf and not outside. “Therefore, taking this step will harm the country and could destroy the Iranian regime,” he said. Concluding the lecture, he said Iran might lay mines around the strait and send submarines, suicide boats, ballistic missiles and anti-ship missile. However, he said, there are other alternatives for exporting oil even if Iran closes the strait. Such proposals include digging a tunnel through the UAE that will link Fujairah to Dubai without crossing the strait, he said.