From 19th century until soon after WWII, major disputes between the countries would typically see a quick de jure settlement once the hostilities (if any) came to a halt and a certain de facto status quo was achieved:
- Wars would end with peace treaties and restoration of diplomatic relations. After Franco-Prussian war, a peace treaty has been signed in four months, in which France officially and in written recognised Alsace-Moselle as German territory, and restored diplomatic relations. Thus, although there were revanchist sentiments, there were no formal territorial disputes between the countries. Likewise, both Crimean war and Russo-Japanese war were concluded with a peace treaties in less than 4 months after the armistice;
- De-facto independent new states (or new government) were recognised by all or almost all other states faster than it happens nowadays. For instance, Greek war for independence ended in 1830, and as soon as in 1832, the independence of Greece was recognised by the Ottoman Empire. Similarly, Romania and Montenegro achieved fully recognised independence in 1878, nearly at the same time as they achieved de facto independence. Serbia might be a counterexample, as it declared independence (and achieved it de facto) in 1869 and it only was recognised in 1878. Brazil declared independence in 1822 and it was recognised by Portugal in 1825. With Spanish American colonies, it took a bit longer, from end of hostilities in 1829 to recognition in 1836 to full diplomatic relations by mid-1840-s. Of course, following WWI, many new countries appeared, and most were relatively quickly recognised.
After WWII and the collapse of colonial empires, the pattern has changed considerably:
- Wars often don't end with peace treaties, and there are territories that remain formally disputed for decades. For example, after WWII, it took 11 years to formally end the state of war and a proper peace treaty between Japan and USSR or Russia has never been signed. For last 73 years, Japan disputes the status of Kuril islands. The two Koreas officially claim each other's territories 65 years after the war ended. Israel holds some of the territories it occupied in 1967 to this day (for 51 years), with status far from being settled.
- There are many de-facto independent, but largely unrecognized states. Taiwan has been independent for 69 years, but is still only partially recognised. The same applies to Northern Cyprus (45 years of de facto independence); Somaliland, Karabakh, Abkhazia, South Ossetia and Transnistria (some 25-30 years); Kosovo (10 years); more recently, east region of Ukraine.
Is this observation valid? Is it true that post-WWII, it has become more common that a de facto state of affairs, e. g., control over territory or independence, lacks formal recognition for a long period of time? Is it possible to quantify this 'more common' claim?
What are some reasons for this? Are there less incentives to reach formal agreement now? Does persistence give more leverage? Do the reasons have to do with international affairs or with domestic politics (e. g., the need to convince the electorate)?