Hammers already booking plane tickets and hotels for Belgium, Croatia and Austria should wait and see whether away fans will be permitted to attend the Europa League away games.
UEFA is due to make a decision next week on 1st September whether away fans will be permitted but the challenges may not stop there even if they give it the green light.
Belgium is listed as an amber country by the UK Government but the Belgium government lists the UK as a red list country enforcing self isolation on arrival.
Croatia and Austria are both listed as green countries by the UK government but that could quickly change as winter approaches with more countries turning amber.
When entering Austria or Croatia you must provide either proof of a double COVID-19 vaccination, evidence of a current negative COVID-19 test, or proof of recovery from COVID-19.
You also need to complete a pre-travel clearance form not more than 72 hours before entry to Austria or Croatia.