The Pentagon has notified U.S. lawmakers of plans to boost U.S. strength in the Persian Gulf in response to Iranian threats to close the Straits of Hormuz.
"The Wall Street Journal" quoted defense officials as saying new mine-detection and clearing equipment and improved surveillance capabilities were part of a build-up in and around the Straits of Hormuz in case Iran attempts to carry out threats to close the straits.
Tehran vowed to cut off shipping routes through the straits if Western states went ahead with plans to impose more sanctions against Iran.
The sanctions aim to force Iran to be more transparent about its nuclear-development program and cooperate with international inspectors who want to verify statements from the Iranian leadership that the nuclear program is meant solely for civilian power generation and not for making weapons.
The report on additional U.S. measures in the Persian Gulf comes as the UN nuclear watchdog, the International Atomic Energy agency (IAEA), said on February 24 that Iran has sharply stepped up its uranium-enrichment drive, tripling its capacity.
The Vienna-based IAEA said in its latest quarterly report about Iran's atomic activities that it has "major differences" with Iran and "major concerns" about its nuclear program, after inspectors probing suspected weapons work this week returned from a failed mission to Tehran.
The conclusion is another red flag for Western governments who are convinced that Iran is pursuing nuclear weapons.
Tehran insists its nuclear activities are intended solely for civilian purposes.
The report says the IAEA "continues to have serious concerns regarding possible military dimensions to Iran's nuclear program."
The UN agency says Iran has now made more than 100 kilograms of higher-enriched material, less than half the amount needed for a nuclear warhead. Iran denies seeking a nuclear weapon.
In Washington, State Department spokesman Mark Toner declined to comment on the report because it hasn't been publicly released.
"We continue to have serious concerns about Iran's lack of compliance, lack of willingness to meet with the international community about its nuclear program," he said.
The IAEA report will be circulated among member states at their next meeting on March 5. It details how Iran has carried out a significant expansion of activities at its main enrichment plant near the central city of Natanz, and also increased work at the Fordow underground facility.
Enriched uranium can be used to fuel nuclear power plants, which is Iran's stated aim, or provide material for bombs if refined much further.
At Natanz, the IAEA report said the number of operating cascades -- each of which contains around 170 centrifuges -- has gone from 37 in November to 52 now.
At Fordow, almost 700 centrifuges are now refining uranium to a fissile concentration of 20 percent and preparations are under way to install many more, the report showed.
The report comes on the heels of a retreat by the latest UN inspection team to visit Iraq. It was their second failed attempt in a month to convince Iran to cooperate.
Based on Reuters, dpa, and AFP reporting