Staunch allies of Ukraine, Poland and the Baltic states -- all neighbours of Russia -- far outstrip NATO's two-percent-of-GDP target on defence.

US Secretary of State Marco Rubio on Thursday told NATO to commit to spending five percent of GDP on defence and dismissed as "hysteria" questions about President Donald Trump's commitment to the alliance.

"Five percent is definitely the goal we want to achieve next year, to get closer and closer to five percent," Poland's Defence Minister Wladyslaw Kosiniak-Kamysz told reporters.

Fearing threats from Russia, Poland has for several years rapidly modernised its military, with a string of arms purchase contracts, mainly from the United States and South Korea.