Why did the Treaty of Versailles cause problems in the future?
The Allied powers wanted to punish Germany for starting the war but thought little of the consequences that would follow from doing so. The German economy lay in ruins. Political and social chaos were the norm. The nascent Weimar Republic was a highly unstable political system built upon rickety foundations. The signatories to the Versailles Treaty overlooked domestic political developments in their desire to seek restitution for Germany's conduct during the war.
Although the treaty imposed a radical program of armaments reduction on Germany, it did not insist on any changes relating to the German Army's primacy in domestic German politics. The moderate socialist government in Weimar were more worried by the threat of extreme leftists than they were of the reactionary right. They saw the army as the only thing standing between Germany and the kind of radical Communist regime recently established in Russia. They used the army to crush Communist agitation, setting a disturbing precedent for what was to follow.
Also, the treaty's provisions relating to armament reduction were never adequately enforced or monitored. This allowed the Weimar government to begin an illegal, surreptitious program of rearmament not long after the Treaty of Versailles had concluded. In some ways, this was a direct reaction to the Germans' exclusion from the Versailles talks, another fundamental flaw in the treaty which turned a peace settlement into a diktat.
President Wilson's failure to get the treaty ratified by Congress was another huge blow. Congress' rejection robbed the treaty of its political authority, leading other countries to lessen their commitment to it. The fragile coalition of interests was beginning to fray, and each signatory nation increasingly looking to advance their own economic interests. Inevitably, this would mean watering down the schedule of German repayment. In subsequent years, reparation payments were indeed modified, most notably under the Dawes and Young Plans.
The initial reparation schedule was both excessively punitive and unrealistic. Apart from anything else, it was always prone to the vicissitudes of the international economy. This was proved in the aftermath of the Great Depression, when German banks failed. It then became necessary for the Allies to impose a moratorium on all future reparation payments.
The Treaty of Versailles caused problems in the future because it treated Germany in a very harsh manner. The people of Germany were angered by the harsh and, in their minds, unfair treatment. In addition, the treaty weakened the German economy, leading to economic problems that also angered Germans. Overall, the treaty made Germans angry and made them more susceptible to supporting radicals like Hitler and the Nazis.
The Treaty of Versailles tried to destroy Germany as a strong country. It attempted to make Germany weak so that it could not threaten the other countries of Europe again. It did this by saying that Germany could not have a large military that had weapons that could be used for offensive purposes. It did this by taking territory from Germany and giving it to other countries. It did this by forcing Germany to pay reparations for the damages caused by World War I. In addition, though this did not weaken Germany, the treaty forced Germany to admit that it had been solely responsible for the war.
Because the treaty weakened and humiliated Germany in these ways, many Germans were very angry about it. They wanted Germany to return to power. They wanted it to reclaim its rightful position as a strong and important country. Because of this, they were willing to listen to radicals like Hitler as long as those radicals promised to get Germany back to its rightful place. In this way, the Treaty of Versailles led to the rise of Hitler and the Nazis. This is how it caused problems in the future.