Yes, you can sue someone living abroad if that person is a Kenyan citizen. If he is a foreigner, then the case will get complicated because enforcing the judgment will be difficult if it is out of the court's jurisdiction.
Another challenge that might also arise is determining the maintenance fee since the cost of living in the USA and Kenya differ.
My advice will be if the father is a Kenyan, you can seek legal advice from your lawyer on whether the case can proceed without the physical presence of the father.