When is the Action Phase and when does it end?

I noticed this in a few parts of the game. Most notably on a Terran research card that lets you Recharge a reinforcement technology card.

The two things I could think of are:

1. The Execution phase.

2. Resolving individual orders in the Execution phase.

Is it either of the above or something else entirely?

In my opinion, Action Phase = Execution Phase

You can't use Recharge more than once per round, this would rather make that card overpowered.

Thanks.

That was my thinking as well. But everywhere I found the question posted it was posted with other questions, which people then skipped it in favour of the other questions.