Bùdòng gǎngkǒu duì běifāng guójiā de hǎiyùn jíwéi zhòngyào.
Ice-free ports are extremely important for shipping in northern countries.
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history
Securing 不冻港口 was a driving aim of Imperial Russia's eastward expansion in the 19th century, leading to the founding of 海参崴 (Hǎishēnwǎi, today's Vladivostok) in 1860 on territory ceded by Qing China.