The US has said it will limit arms sales to Saudi Arabia amid concerns over civilian casualties linked to air strikes in Yemen.
Precision-guided weapons will no longer be delivered, a Pentagon official said.
President Barack Obama's administration said it was concerned over "flaws" in the way air strikes are targeted in Yemen.
In October, more than 140 people were killed in a strike on a funeral in the country.
A Saudi-led coalition, which is attempting to support the elected government against Iranian-backed Houthi rebels, was blamed for the attack.
White House National Security Council spokesman Ned Price later warned Saudi Arabia that US security co-operation was "not a blank cheque".
But while some sales are being scaled back, the US said it will continue to provide Saudi Arabia with intelligence focused on border security.
It will also provide training for pilots involved in the Saudi-led air campaign, to avoid civilian casualties wherever possible, the official said.
Other contracts are expected to go ahead such as a deal worth more than $3bn (£2.4bn) to supply military helicopters.
The Saudi-led coalition is fighting the Houthi rebel movement in Yemen.
Thousands of civilians have been killed and nearly three million people have been displaced in the country, one of the region's poorest, since the war began in 2014.
The Houthis took the capital Sanaa, forcing Abdrabbuh Mansour Hadi's government to flee. Some ministers have since returned to the city of Aden.
Saudi Arabia has denied causing large-scale civilian deaths, saying it is making every effort to avoid hitting civilian targets.