Can you confirm if you are married? If you are married and your partner is a US resident, who did not move out of the US, then you can file jointly with your partner and then you would be able to claim the dependents and the associated credits.
Assuming that is not the case, and you are a dual status alien filing on a 1040NR you can't claim your children as qualifying dependents and therefore can't claim the child tax credit.
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