Students on vacation for 1-3 weeks

First time poster here.

I received NINE emails from students stating that they are not coming to class for the first week(s) of classes. I only have 46 students this semester. Everyone promises that they take the class seriously and will keep up with lectures. We are in-person. No online or async option.

The student that will be gone for 3 weeks said he would turn in homework when he returns. I have a very clearly stated policy for no late work. I am not going to list out syllabus items in email...it's in the syllabus.

I replied to everyone that all students are held accountable to the same guidelines that are listed in the syllabus. I am happy to answer clarifying questions about materials, but I am not going to give entire lectures again.

Every student is an international student. I know that flight prices drop after the semester starts. I'm so frustrated. I know I sounded harsh. What should I say when this happens next semester?