Well, my investigation yields this:

HKG-SIN is cut from Apr 7 to Apr 15. That would be 9 flights.

SIN-HKG is cut from Apr 8 to Apr 16. That would be 9 flights as well.

Total = 18.

Flights resume on Apr 16, as far as United.com shows me at the moment.

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When once you have experienced being a 1K, you will forever fly the friendly skies with your eyes set on 100% mileage bonus and SWUs, for there you have been, and there you will always long to return, every year!