Are there nonstop flights from Washington (IAD) to Santiago (STI)?

No. The fastest connection is via Providenciales, about 3h 41m of total flying time.

What is the fastest connection from Washington (IAD) to Santiago (STI)?

via Providenciales ≈ 3h 41m, via Philadelphia ≈ 3h 59m, via Fort Lauderdale ≈ 4h 10m (estimated flying time, excluding layovers).

from 30,000 ANA miles (economy, one way, based on the published award charts).

Washington Dulles International Airport (IAD) to Cibao International Airport (STI)・2,270 km

No nonstop flights. The fastest connection is via Providenciales (PLS), about 3h 41m of flying time (layover not included).

With milesANA 30,000 miles+ (via EWR)Economy, one way, estimate. Tap a connection for miles by cabin.

None.

10 one-stop options, sorted by estimated flying time. Tap one to see the airlines on each leg and booking links.

Times are estimated from distance. Check schedules, frequency and availability with the airline or a booking site.