The USA, the UK, Australia and Canada as a committed military and cultural alliance would have immense reach. Superbly endowed with human capital, physical resources and a martial and self-correcting culture, that alliance would attract Israel, India, Japan, Eastern Europe. There would be huge gains for the security of all. Oh, and include brave Denmark as a founding member.
US foreign policy should remorselessly promote a formal Anglosphere alliance . That means winning hearts and minds in countries with an anti-American MSM nearly equal to your own. That means preferential treatment both ways to the countries who've fought together through several wars. Screu the EU.
I agree there's a problem with indigenous Islamists. That needs fixing under any scenario; reverse dhimmitude, perhaps.
This is a long-term project. Articulate it now. Start soon. Meanwhile many of us suave British males have been breeding with your most beautiful womenfolk and re-colonising the USA. There's Mick Jagger, Paul McCartney, Guy Ritchie, me, und,und,und..