The administration of the United States president on Friday bypassed Congress to approve the sale of $8.1 billion worth of arms to Saudi Arabia, the United Arab Emirates and Jordan.

The deal would "deter Iranian aggression and build partner self-defense capacity" of US allies, Secretary of State Mike Pompeo said in a statement.

“These sales will support our allies, enhance Middle East stability, and help these nations to deter and defend themselves from the Islamic Republic of Iran,” he added, referring to heightened tensions with Tehran.

The secretary of state notified Congress of his decision to use an emergency loophole in the law regulating the export of arms to sell surveillance equipment, precision munitions and other supplies to Saudi Arabia, the UAE and Jordan.

"Delaying this shipment could cause degraded systems and a lack of necessary parts and maintenance that could create severe airworthiness and interoperability concerns for our key partners, during a time of increasing regional volatility," Pompeo said.

The instance is to be a “one-time event,” he said.

Congressional opposition to the US' military support to Saudi Arabia has been on the rise in recent months and lawmakers have managed to block arms sales for more than a year and a half.

Legislators are concerned about civilian casualties in the military operation led by Saudi Arabia in Yemen and outrage over the assassination of US resident and journalist Jamal Khashoggi at the Saudi consulate in Istanbul last October by suspected Saudi agents.

It also comes as the US is to send 1,500 troops as well as weaponry to the Middle East to counter an unclarified threat posed by Iran.

In April, Trump vetoed a resolution passed by Congress to end US military support to the Saudi-led war in Yemen.

The measure won the support of most legislators following Khashoggi's assassination on Oct. 2, 2018. Trump, however, has defended US ties with the kingdom despite the murder.