By Dan De Luce
Gates was due to hold talks with Abu Dhabi Crown Prince Sheikh Mohammed bin Zayed al-Nahayan, who is also the deputy commander in chief of the armed forces in the United Arab Emirates, as part of high-stakes diplomacy designed to tighten pressure on Iran over its nuclear programme.
The defence secretary's visit came a day after Gates appealed to Saudi leaders to back the US-led drive for punitive measures in discussions in Riyadh, the latest in a series of high level visits to the region by President Barack Obama's deputies.
The American focus on the Gulf prompted a warning on Thursday from Iranian President Mahmoud Ahmadinejad, who accused "corrupt" powers of destabilising the Gulf.
"What are you doing in our region?" Ahmadinejad said in a speech in the Gulf port of Bandar Abbas.
"Why have you sent your armies to our area? If you think you can control the oil of Iraq and the Persian Gulf, you are mistaken," he said.
The Iranian president has traded barbs with Gates this week, as Ahmadinejad's visit to Afghanistan overlapped with the US defence secretary's trip there.
In an earlier stop at a US military base in Southwest Asia en route to Abu Dhabi, Gates expressed amusement about how he and the Iranian president had "exchanged a few words through the media" this week over Afghanistan.
Before his meeting with the crown prince, Gates toured the vast Sheikh Zayed mosque in Abu Dhabi, named after the founder of the UAE, and told reporters the United States and the UAE had been "close partners" for years.
With Washington striving to disrupt funding of Iran's nuclear work, Gates planned to discuss with UAE leaders how "to increase pressure" on companies doing business in Dubai with links to Iran's powerful Revolutionary Guard, a US defence official told reporters.
The UAE has a large Iranian expatriate community and is a major conduit for Tehran's trade with the outside world.
Gates' visit also highlighted Washington's lobbying of Gulf states to use their oil resources to sway China, which has been reluctant to back sanctions at the UN Security Council.
The Americans have asked the Saudis and Abu Dhabi leaders to reassure Beijing that they would be prepared to offset any shortfall in Iranian crude shipments.
The Washington Post has reported that Saudi Foreign Minister Prince Saud al-Faisal travelled to Beijing early this month to discuss the issue.
The role of the Gulf states is pivotal for the US diplomatic strategy, as they can exert genuine economic pressure on Iran while also ensuring a smooth flow of global oil supplies in the case of a possible cutoff of Iranian oil exports.
On Wednesday, Gates told the Saudis that after Iran had "largely rebuffed" US overtures for a conciliatory dialogue, the Obama administration was now focused on ramping up pressure on Tehran, the defence official said.
But Gates stressed in his talks that the United States wanted to see financial sanctions targeted on Tehran's Revolutionary Guard and not the country's population.
Gates also was expected to discuss a broader US effort to boost air and missile defences in the Gulf in the face of Iran's growing arsenal of ballistic missiles, a serious concern for Abu Dhabi.
The United States has promised to speed up weapons sales to the UAE and other Gulf states, which have bought billions of dollars worth of American weapons in recent years.
US officials believe the arms buildup in the Gulf sends a clear signal to Iran that its nuclear and missile programmes are counter-productive.
