HONOLULU (USA) - The United States announced Thursday the signing of a $30 billion arms deal to provide Saudi Arabia with 84 new fighter jets, a move it said sent a "strong message" to the Gulf region.

The announcement came with tensions between Iran and the United States on the rise after Tehran threatened to close the Strait of Hormuz to oil tankers if Washington implements a new raft of sanctions over its nuclear program.

The $29.4 billion deal, which was signed on Saturday in Riyadh, will supply 84 new Boeing F-15SA aircraft, modernize 70 existing planes, and also includes munitions, spare parts, training and maintenance contracts, US officials said.

"This sale will send a strong message to countries in the region that the United States is committed to stability in the Gulf and broader Middle East," senior State Department official Andrew Shapiro told reporters in Washington.

"It will enhance Saudi Arabia's ability to deter and defend against external threats to its sovereignty."

The deal, announced formally on Thursday in Hawaii as President Barack Obama vacationed in his native state, was first unveiled in October 2010 as part of a $60 billion US arms sale to Saudi Arabia.

In Honolulu, White House deputy spokesman Josh Earnest said the agreement would support more than 50,000 American jobs at a time of high unemployment and provide a $3.5 billion annual boost to the US economy.

The delivery of the whole package will unfold over 15 to 20 years and also includes Black Hawk and Apache attack helicopters, defense officials said.

Iranian Vice President Mohammad Reza Rahimi has warned that "not a drop of oil will pass through the Strait of Hormuz" if the West follows through with planned additional sanctions against Iran over its nuclear program.

Such a move could cause havoc on world oil markets, disrupting the fragile global economy, although analysts say the Islamic republic is unlikely to take such drastic steps as it relies on the route for its own oil exports.

Shapiro, the assistant US secretary of state for political-military affairs, said the Saudi deal had much to do with countering Iran's perceived threat.

"They've had border security issues. They've had threats in the Gulf as well. And clearly one of the threats that... they face, as well as other countries in the region, is Iran."

However, he added: "This is not solely directed towards Iran. This is directed towards meeting our partner Saudi Arabia's defense needs."

Shapiro also said that, in line with US law, it was determined that the sale would not undercut Israel's qualitative military edge.

Speaking at the same press conference, senior Pentagon official James Miller said the new F-15s "will be the most capable and versatile aircraft in the Royal Saudi Fighter inventory."

"The F-15SA will have the latest generation of computing power, radar technology, infrared sensors and electronic warfare systems," he said.

They will also "be able to strike targets day or night in all weather, with a variety of precision-guided munitions."

With the new fighters' communication systems, US and Saudi pilots will be able to operate "effectively" together in the same air space, Miller said.

First deliveries of the aircraft will be made in early 2015, while the modernization of existing planes will start in 2014 and the first payments for the deal are expected in the coming weeks and months.