What happens to visas in the event of war?

Hi everyone,

This is obviously a highly hypothetical question, but one that has been on my mind given the strange geopolitics of late.

If United Kingdom became entangled in a military conflict with the United States over Greenland, what would be most likely to happen to UK visa processes and statuses that involve the US, specifically:

1. Pending fiancée (prospective marriage) and spousal visas from the US
If someone has already applied for entry clearance from the US to come to the UK as a partner or fiancée, what would happen to those applications? Would they be cancelled, paused, fast-tracked or dealt with in some other way?

2. Current US spouses in the UK on spousal visas
For those US citizens already living in the UK on a spousal visa, and those applying for further leave to remain or indefinite leave to remain, how might their immigration status be affected?

I am particularly interested in whether:

• There is any official UK government policy or published contingency guidance that addresses visa processing in the event of war with a specific country (in this case the US).
• There are any precedents in British immigration law or practice for what happens to existing statuses and pending applications when diplomatic relations break down.

I understand this is still far-fetched scenario for now, but even knowing how the Home Office treats visa administration during diplomatic breakdowns or sanctions could be informative for understanding the system.

Thanks in advance for any insights or links to guidance you might share.

Cheers.