Chad withdrew hundreds of troops from neighbouring Niger, where they were helping local forces fight Boko Haram Islamist militants, humanitarian sources and officials said.
The pull-out over the past two weeks could weaken a region-wide struggle against the militants who have killed tens of thousands of people, forced many more to flee and triggered a humanitarian crisis.
There was no immediate explanation or comment from defence officials in Chad. The move came a month after the vast central African country complained about an unexpected U.S. travel ban imposed on its nationals.
Chad warned at the time the order could affect its security commitments, which include its involvement in the U.S.-backed fight against Boko Haram.
Residents said the withdrawal had already had an impact on Niger’s Diffa region, which has seen a string of attacks by Boko Haram militants crossing over from their base in neighbouring Nigeria.