The engineering vehicles will be used to construct positions, fronts and tunnels in areas occupied by YPG in Syria, according to the sources.
A convoy of 100 U.S. trucks were also seen carrying closed chests, tankers and SUVs from Iraq to a YPG occupied area in Syria on April 2.
Washington maintains nearly 2,000 troops in Syria following its announcement that only a few hundred would remain after withdrawal efforts.
U.S. President Donald Trump declared victory over IS and signaled a “slow and highly coordinated pullout” of U.S. troops from Syria last December.
The White House announced in February plans to keep 200 troops in northeastern Syria as part of an international peacekeeping force, in addition to 200 others to secure a garrison at a strategic Syrian border town.
Although the date set for the pullout has passed, the U.S. has yet to reduce its military presence in Syria.
On the contrary, 300 trucks were sent to areas occupied by YPG militants in Syriafrom the Iraqi side at the beginning and the end of February.
On Feb. 4, the U.S. delivered nearly 150 truckloads of armored vehicles and equipment to depots belonging to the YPG in Harab Isk and Sarrin.
The Pentagon announced March 12 that $300 million would be allocated to the YPGfrom its fiscal year 2020 budget.
Turkey has long criticized the U.S. working with and supplying arms and ammunition to the YPG to defeat IS.
Turkey deems the YPG as a terrorist group due to its links to the PKK, which is listed as a terror group by Ankara, the U.S., and the EU.
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