In the 2000s, the government began leaning towards NATO, and a deeper cooperation with the alliance was set by the NATO-Ukraine Action Plan signed in 2002.
It was later agreed that the question of joining NATO should be answered by a national referendum at some point in the future.
The first of these periods occurred briefly during and immediately after the German occupation near the end of World War I and the second occurred, also briefly, and also during German occupation, during World War II.
However, both of these first two earlier periods would eventually see Ukraine's territories consolidated back into a Soviet republic within the USSR.
A Cossack republic emerged and prospered during the 17th and 18th centuries, but its territory was eventually split between Poland and the Russian Empire, and later merged fully into Russia.
During the 20th century three periods of independence occurred.
Before its independence, Ukraine was typically referred to in English as "The Ukraine", but sources since then have moved to drop "the" from the name of Ukraine in all uses.
Nonetheless it formed a limited military partnership with the Russian Federation and other CIS countries and a partnership with NATO in 1994.
After a final resurgence under the rule of Vladimir II Monomakh (1113–1125) and his son Mstislav (1125–1132), Kievan Rus' finally disintegrated into separate principalities following Mstislav's death.
By 4,500 BC, the Neolithic Cucuteni-Trypillian Culture flourished in a wide area that included parts of modern Ukraine including Trypillia and the entire Dnieper-Dniester region.
During the Iron Age, the land was inhabited by Cimmerians, Scythians, and Sarmatians.
In 2013, after the government of President Yanukovych had decided to suspend the Ukraine-European Union Association Agreement and seek closer economic ties with Russia, a several-months-long wave of demonstrations and protests known as the Euromaidan began, which later escalated into the 2014 Ukrainian revolution that led to the overthrow of President Yanukovych and his cabinet and the establishment of a new government.
These events formed the background for the annexation of Crimea by Russia in March 2014, and the War in Donbass in April 2014.