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(CNN) —  

The Trump administration is reinforcing its controversial military relationship with Saudi Arabia by preparing to send hundreds of troops to the country amid increasing tensions with Iran.

Five-hundred troops are expected to go to the Prince Sultan Air Base, located in a desert area east of the Saudi capital of Riyadh, according to US two defense officials. A small number of troops and support personnel are already on site with initial preparations being made for a Patriot missile defense battery as well as runway and airfield improvements, the officials said.

The US has wanted to base troops there for some time because security assessments have shown Iranian missiles would have a difficult time targeting the remote area.

The decision comes as US and Saudi relations remain extremely sensitive amid bipartisan congressional anger how the administration has handled the murder of Jamal Khashoggi.

But the Trump administration has said it is committed to trying to help protect Saudi Arabia against Iranian aggression.

Last month the administration announced it was sending 1,000 additional troops to the Middle East as Iran tensions flared but did not specify which countries they were going to. The forces going to Saudi Arabia are part of this deployment.

Congress has not been formally notified of the deployment, although one official told CNN that they had been given an informal heads up and an announcement is expected next week.

The notification to Congress will provide more precise details about the US military deployments to the region that have already been publicly announced.

Commercial high-resolution satellites, captured by Planet Labs and obtained by CNN, show an initial deployment of US troops and support personnel to the air base in mid-June, according to Jeffrey Lewis, director of the East Asia Nonproliferation Project at the Middlebury Institute of International Studies at Monterey, who has studied the new images.

Subsequent imagery captured in late June and early July appear to show preparations being made to the site ahead of the deployment of US troops, Lewis said.

“A small encampment and construction equipment appeared at the end of a runway by June 27, suggesting that improvements are already underway. The encampment to the east of the runway is typical of Air Force engineering squadrons deployed overseas,” he told CNN.

The US hopes to be able to fly stealth, fifth-generation F-22 jets and other fighters from the base, according to officials.