The Obama administration is terminating some sales of military arms to Saudi Arabia over concerns about the killing of civilians in Yemen by a Saudi-led coalition.
The sales being cancelled involve precision-guided munitions. An official said the decision reflects deep US concerns about the way Saudi Arabia is choosing targets.
But the US is ramping up support for Saudi efforts elsewhere.
The official said the US is increasing support for Saudi Arabia's border defences. The kingdom has been concerned about extremists coming over the border to launch attacks.
The White House announced a review of military support for the Saudi coalition following the October bombing of a funeral hall in Yemen.