Is proof of Health Insurance checked on a 3-day visit? If so, would a Heath Insurance ID card be needed for this, or would the Travel Accident Insurance provided through some Visa cards be sufficient? (its not quite my definition of health insurance, but it covers some health related trauma)
U.S. Passports & International Travel
You do not need a visa to enter Ukraine for visits of up to 90 days in any 180 day period, but must be able to provide proof of valid health insurance and sufficient funds for the duration of your stay.