The United States has announced a $3.48 billion arms deal with the United Arab Emirates as part of a wider American effort to build up missile defenses among Gulf allies to counter Iran.

The announcement late on Friday came amid threats from Iran to close the vital Strait of Hormuz if Western countries press ahead with punitive sanctions and a day after the United States sealed a $30 billion arms deal to provide another Gulf ally -- Saudi Arabia -- with 84 new F-15 fighter jets.

The agreement with UAE includes two sophisticated missile defense batteries, 96 missiles, two radars, spare parts and training, Pentagon press secretary George Little said in a statement.

"This sale is an important step in improving the region's security through a regional missile defense architecture," Little said.

Amid rising tensions with Iran, the US arms deal is the latest in a series designed by Washington to bolster missile defense weaponry in Gulf states that are increasingly anxious over Tehran's missile arsenal and nuclear program.

The United States and Saudi Arabia unveiled a $1.7 billion deal earlier in 2011 to boost the country's Patriot missile batteries and Kuwait has purchased 209 GEM-T missiles worth $900 million.

The regional missile defense plan pursued by President Barack Obama's administration calls for land-based interceptors to knock out incoming missiles backed up by a detection network on US Navy Aegis-class warships.

US officials say the arms sales in the Gulf send a signal to Iran that its missile build-up and nuclear program are undermining its security and leaving the country isolated.

Iran meanwhile kept tensions simmering on Saturday, saying it was preparing a series of missile tests near the strategic Strait of Hormuz.

The US military has warned a closure of the strait "will not be tolerated" after Iranian Vice President Reza Rahimi's threat this week that "not a drop of oil" will pass through the channel if more Western sanctions are imposed over Tehran's nuclear project.

US officials said the United Arab Emirates is the first country to purchase the advanced anti-missile network known as Thaad, or Terminal High Altitude Area Defense System.

"Acquisition of this critical defense system will bolster the UAE's air and missile defense capability and enhance the already robust ballistic missile defense cooperation between the United States and the UAE," Little said.

Both the United States and the UAE want to see "a secure and stable" Gulf region, he said.

The Pentagon also said it had awarded US defense giant Lockheed Martin Corp. with a contract worth $1.96 billion to supply the United Arab Emirates with the two Thaad anti-missile batteries.