The United States has decided to limit military support to Saudi Arabia’s campaign in Yemen because of concerns over widespread civilian casualties and will halt a planned arms sale to the kingdom, US sources say.

An Obama administration official, who spoke on condition of anonymity, told Reuters news agency that “systemic, endemic” problems in Saudi Arabia’s targeting drove the US decision to halt a future weapons sale involving precision-guided munitions.

“We’ve decided not to move forward with some foreign military sales cases for air-dropped munitions, PGMs [precision-guided munitions],” the official said.

“That’s obviously a direct reflection of the concerns that we have about Saudi strikes that have resulted in civilian casualties.”

A second official confirmed the decision to suspend the sale of certain weaponry.

There was no immediate comment from Saudi embassy officials.

A specific case put on hold appeared to involve the sale of hundreds of millions of dollars worth of guidance systems manufactured by Raytheon that convert dumb bombs into precision-guided munitions that can more accurately hit their targets.

The White House launched a review of US assistance for the Arab coalition assembled by Saudi Arabia after planes struck mourners at a funeral in the capital Sanaa in October, killing 140 people, according to one UN estimate.

Civilian casualties

The air strikes took place after the coalition received incorrect information from Yemeni military figures that armed Houthi leaders were in the area, an investigative body set up by the coalition said in October.

The UN human rights office said in August that the coalition was responsible for roughly 60 percent of the 3,800 civilians killed since March 2015.

The US official said that the administration would not halt refuelling of the coalition planes.

READ MORE: UNICEF – One child dies every 10 minutes in Yemen

“For now that’s not going to be touched. Again, the review could continue and people could make a different decision in the coming weeks,” the official said.

The decision to suspend the arms sale to the Saudis marks a reversal for the administration.

Officials have long argued that supplying “smart weapons” helped in reducing civilian casualties.

Earlier this year, the US military reduced the number of military personnel coordinating with the coalition’s air campaign, shrinking it to six people from a peak of 45 personnel.

In May, the US suspended sales to Saudi Arabia of cluster munitions, which release dozens of bomblets and are considered particularly dangerous to civilians.

Last week, the US state department announced plans to sell Saudi Arabia CH-47F Chinook cargo helicopters and related equipment, training and support worth $3.51bn.

The US said the weaponry would help Saudi defend its border, not conduct offensive operations in Yemen.

The Arab coalition intervened in Yemen’s civil war in March 2015 and has launched thousands of air strikes against Iran-allied Houthi fighters.

For its part, the coalition has accused the fighters and their allies of firing ballistic missiles towards Saudi cities and border posts, as well as hampering aid operations in Yemen.