Note: this is a thread I started on TMP, but I think it can be of interest also here... for some aspects I can be linked to the WW2 period, but I envision it more as an interwar thing, and covering china Back of Beyond seems the right spot.
Enjoy!

Actually china was really keen on getting german help as far as 1938-39. The stopped contacts only when in 1940 Germany recognized the pupped government estabished by the Japanese. The point is until 1938 Germany could have still supplied China without troubles by sea, then if the bargained with Soviet union the could have quickly established a landline much more effective than the Burma road. This assuming the Japanese had indeed prosecuted the war has they did. And even that until 1938 german money loans and military export were significant.
Now, if Hitler actually expanded contacts and supplies (a thing he could have done without any problem, remember the cut back in sales and loans was a decision on germany part following their siding with Japan) what effect that would have done on Japan policy?
Certianly nothing prevented Germany to set up something like the Condor Legion to support Jiang. While one can say China is not spain, the dynamic of the war and the fact that Japanese forces were not big could have made significant contributions (remember even limited soviet contributions were able to create local swing effects).
Now let me to fantasize a bit on a potential scenario…
First of all some random thoughts one the player, then a more coherent approach…
Lets say that in 1937 the German deployed several fighter squadrons to Shanghai in advance and the german pilot are able to inflict losses on the Japanese. Also the appearance of a european power in the arena could have modified the diplomatic situation. Probably forcing an halt on japanese operations. The fact is that the Japanese wanted only to force concessions from Jian, they knew that they cannot completely invade and occupy China. thus if we remove the idea that they can inflict a "decisive" military defeat on China their own strategy had to change. Now let us say the reach a settlement and one that do not satisfy the army…
yet they had to rewrite their strategy. Approach with soviet union (itself a GMD sponsor) it is not attractive. Germany is almost the enemy… so they had to look to the west.
Increased connections between Jiang and Hitelr would have probably shifted Jiang more and more toward the axis camp… but…
What to do with soviet union? Certainly Stalin was happy to ditch Mao in favor of a firendly and anti-japanese Jiang, but now?
Stalin is in the same quandary as Japan, who will become friend with me? but considering how Machiavellian he could be let say that he goes along with the soviet-nazi pact in the future…
The western countries were not overly friend with Jiang and were keen on maintaining their own concessions and trade rights… and if China, Soviet Union and Germany seemed to become closer you can bet they would have been very very unhappy.
Mao… beacuse in the end the enemy of my enemy is my firend I bet he would have tried a way to get in touch with the west…
Now let move on a more coherent scenario…
Hitler decides to take a longer ranged approach to his plan for world domination. He bet on creating a solid axis with China to surround and then crush the communism. in 1936 he indeed increases the links with china and in 1937 after the Marco Polo bridge incident side openly with china and send a small but well trained contigent to china.
The germans are able to stop the Japanese assault on Shanghai and tokyo is forced to settle for a settlement. In the end the only thing gained are several remote areas in the north, some limited concessions along the coast and a loss of prestige. Jian is thus able to enhance his reputation, remove some less than friendly figure in the goverment (he clear the score after the Xian "incident") and finally crush the communist with Stalin appearing more or less neutral.
In 1938 China and Germany sing the anticomintern Pact and strenghten relations. The chinese agree on a german concession and naval base on tsingtao.
The new german outlook cause some shockwaves in europe. Mussolini's Italy became less and less friendly with Germany and Germany seemed not overly interested in actively courting Italy. UK and France Are not overly happy with the situation so they start to try again to form a partnership with Mussolini. That meant steadily closing on supplies for the republicans in Spain.
Stalin decides that in the end the Spanish republic is not worth too much troubles and quietly severs the contacts with the republic and simply let it die. Franco victory is a bit less bloody and happens some months early.
Hitler is keen in building an overland link with china and preserve the shipment of valuable materials (including a thing called tungsten…), so he decides to postpone his grandiose plans for world conquest until 1943-44 and instead build a strong china and play Soviet Union… after all it is considered not a threat (historically due to good intelligence sources the soviet unition threat was storngly downgraded) in 1939 the Molotov-Ribbentrop-Kung is signed. It is an awkard alliance but it allow Germany access to chinese and soviet excess resources, while in return germany helped china and make some concessions to Soviet Union. And Stalin has time to rebuild after the purges. The historical event on the manchurian border happens (nomohan) due to the lack of clarity in the border and to the facgt that the Kwantung army is definitely restless having to avenge the previous setbacks in china… end result is that Japan finally swallow the pill and enter in serious talks with the western allies.
Germans build several dockyanrd in Hankow, Tsingtao and Vladivostok to give soviet union and china a blue water navy. Germany strategy is to smash the west first then with the help of Jiang have the final showdown with uncle joe. (Yes it is far fetchedm but the sequential approach floated several times in the OKW and OKH, also I am assuming Hitler decided for a measurate and calculate approach, let say he really really want the Z plan completed before doing anything, with chinese resources that oculd have been made).
Now the west is not happy. With the help of italy they build a Balkan entente with romania and Hungary, while Yugoslavia became close to Hitler. In 1938-39 chamberlain and Blum government fell replaced by more conservative government, the diplomatic situation favoured a limited rearmament of both France and Uk while Italy continues with the "historical" approach but with closer ties with the west.
One of the effect of the west moves is to push moscow closer to germany due to uneasy with the balkan entente and support for Japan after nomohan the fact that in the end they are not looking more friendly than the "axis".
USA follow almost the same historical approach with Japan replaced by China, Jiang closeness with hitler has the same effect on Roseevelt that japanese encroaching had historically. Also the embrionic chinese blue water navy (built with german assisantce) is sufficient to give a scare ot everyone
My scenario postulates a Nazi-soviet joint move against czeckoslovakia and poland in september 1943. France, Italy and UK honor their promises and intervene. Poland fought valiantly but is overwhelmed, the czeck, supported by the balkan entente are another matter. Yugoslavia enters the war on germany side and that creates a big stalemates in the balkans. A German offensive in the west is stopped in the low countries (Belgium and the Netherlands had closed on the allies side).
In asia, in accordance with the plan to create a worldwide blockade agaisnt england (and thus reverse WW1 blockade) Jiang declared the war and start to harrass allied traffic in the west pac, plus launch an invasion of tonkin with the aim to then remove Malaya and the east indies from allies. also attacks on the eurpanes settlement (with reduced garrisons) are conducted. Og course Tokyo declared war in september 1943 to honor yis commitment, and when american property in china is attacked and american ships are sunk by german and chinese u-boots and raiders and with their econiomic interests in china threathene rosevele is able to obtain a war declaration.
The idea is that, except some limited upgrades (like Z plan germans, expanded soviet fleet with some of the projected cruisers, battlecruisers and battleships) even with the rearmament of the 1939-1943 the majority of equipment will be still "early war".
I know this scenario is based on several big what if (mainly different priorities from Hitler) but I think it has a logical flowing…
Ideas?