Rwanda: Yellow fever vaccination required?

The US Department of State says yes, but as far as the Rwandan government is concerned, the US Department of State is a secondary source. Oddly, they say

Yellow fever vaccination required upon entry

This is odd because the vaccination requires 10 days before it is effective. Source: http://travel.state.gov/content/passports/en/country/rwanda.html

TIMATIC says no:

 Rwanda (RW)
Vaccinations not required.
Recommended:
- Vaccination against yellow fever for all passengers over 1 year of age.

(Retrieved via klm.com)

But what does the Rwandan government say? The best I could find, via the Directorate General of Immigration and Emigration, is

Health Requirements:

A vaccination certificate may be required at the border post. In the event of a major disease outbreak, specific requirements could be set and put to the knowledge of the public.

(emphasis added; source: https://www.migration.gov.rw/index.php?id=13)

Is there any authoritative (and unambiguous) source indicating the requirements for entering Rwanda as a tourist?