Is it safe to re-index an AWS Cloudsearch index while another indexing operation is running?

I've just started a re-index of my Cloudsearch index because I've added a new field and changed the data type (text to literal) of another field. I've just realized I accidentally set the literal field to be non-searchable, and need to change.

The full re-index should probably take about 3-4 hours, but I'd like start over. I'm sort of nervous about re-indexing while another re-index is running, because there's no option to let you cancel an in-flight indexing operation. I can't see anything in the docs about this. Is it safe?