Leading politicians from all six political parties represented at the Riigikogu have, despite their differences on other topics, agreed on the need to boost defense spending to 5 percent of GDP per year,

Ralf Stegner, a member of Germany's Social Democratic Party, called Trump's comments "delusional and truly insane." Poland has backed Trump's demand.

Europe's military heavyweights have already said that meeting President Donald Trump's potential challenge to spend up to 5% of their economic output on security would be challenging.