What is the current status of airside connections at LAX?

I know that Terminals 4-8 have always been connected by tunnels, and a new bridge connecting the Tom Bradley International Terminal with Terminal 4 (and thus 5-8) at the airside was recently constructed. I also know that there are no physical airside connections among Terminals 1-3 and TBIT.

Recently, Delta Air Lines moved its operations from Terminal 5 to Terminals 2 and 3, and there is now a connection bus that operates between these two terminals. I also read some news that there may be a bus connecting Terminal 3 with TBIT, though I'm not sure.

• Is the airside bus between Terminals 2 and 3 fully airside, or does it require a security check?
• Is there an airside bus between Terminal 3 and the Tom Bradley International Terminal? If so, does it require a security check?
• Do any of these buses have restrictions on who can use it (e.g. does moving from TBIT to Terminal 3 require a Terminal 3 boarding pass)?
• What about Terminal 1? Does it have any sort of airside connections to the other terminals?

After doing some research, I found this: https://pro.delta.com/content/agency/us/en/news/news-archive/2017/may-2017/delta_s-relocation-to-lax-terminals-2-and-3-begins-evening-of-fr.html

Immediately following the move, Delta customers will enjoy:

• Faster and more convenient connections to flights operated by Delta’s joint venture and SkyTeam partners in Terminals 2, 3 and TBIT via an airside bus that prevents customers from having to leave and re-enter the secure area

Are these buses restricted to Delta passengers, or can other passengers use them? Do they allow passengers to go both ways, or can passengers only go one way on one or more of these shuttles?