The United States has delivered a fresh supply of ammunition to Syrian Arab fighters ahead of an expected stiff battle with Islamic State as they push toward the Syrian town of al-Shadadi, a key logistics hub for the group, U.S. officials tell Reuters.

The munitions were shipped into Syria over land in recent days to Syrian Arab forces fighting in the northeast part of the country, said the officials, who spoke on condition of anonymity due to the sensitive nature of the operation. It appeared to be the third delivery of ammunition to the Syrian Arabs since the United States started supplying them with an airdrop in October.

The Syrian Arabs are allied with Kurdish fighters, and the initial shipment of U.S. ammunition unnerved NATO ally Turkey, which is sensitive to any operations that could benefit Syrian Kurdish YPG militia. […]