While I know how unnecessary my paranoia is regarded, there is another way to do this. Going into parts unknown and unexplored, wherein Ean has a high chance of taking a long, if not everlasting dirtnap, without covering our homebase, that is going to be sucked dry by space squids, doesn't seem too good of an idea.
Before mounting an expedition, we send Artemis on another run to warn the Chinese about the tree and in the meanwhile, we go and parley with the North, preferably with the Shaman, but the ruler will do too. Strike a deal/an alliance, if only temporary, between the two Empires, to both prevent aggression from either side and prepare for an intervention in China, in case the Immortals fail. Because, hey, Ean may be gone a long time. Plus, it'll give Sekhenun time to hopefully figure the Rift out.
Also, anyone ever thought that the one behind the North is Edem's pappy? The timeline matches up, as does Edem's report of "nothing weird going on, nothing weird at all, no sir, Ean, sir" and the secrecy (Last time the two met, the farewell wasn't all that pleasant).