DoD upgrade is for AMS-JFK only as the KLM agents at Schiphol can't look into Delta's systems. If you want a one-way upgrade you need to contact Delta before KLM takes control.

Basically, the DOD official upgrade options for Delta flights ex-AMS are :

- OLCI offer (very rare on Delta metal ex-AMS)
- Kiosk (cash) offer (also very rare while checking at AMS)
- miles or a GUC & co-pay (if applicable) at KLM ticket counter, KLM lounge or transfer-desk, always available if there are seats

For DL tickets on DL flights (until June), it's 25,000 skymiles +:

V - €450
X - €400
T - €350
U - €300
L - €250
K - €200
Q - €150
H - €100
M and up: no co-pay needed

- Full cash buy-up offer, based on a different rate chart (always the most expensive); €849/€859 AMS-JFK, always available if there are seats