I thought the Vulcan situation at Ascension was more to do with pre-existing agreements and rules. The American base commander's orders (as of before the conflict) said he couldn't directly support offensive operations launching from the Wideawake. It wasn't his job to change US Foreign Policy unilaterally so he reminded the British officer in charge of the Ascension operation that he couldn't support the Vulcans as it stood while at the same time asking his CoC if he could. The DoD without question then sent him the required change in orders along with all the other assistance they gave us. However, some senior folks (like Nott) took this the wrong way as they weren't briefed on all the details.
That's not probably not how it happened exactly but it's the impression I got from Vulcan 607.