Pakistan, April 25 -- Europe's "biggest, most important question" is whether the United States is ready to be a loyal NATO partner in case of a Russian attack, Polish Prime Minister Donald Tusk told the Financial Times.

He also called for the European Union to become a "real alliance" in protecting the continent, reflecting growing worries about US President Donald Trump's unpredictable policies and threats towards his European partners.

"For the whole eastern flank, my neighbours.? the question is if NATO is still an organisation ready, politically and also logistically, to react, for example against Russia if they try to attack," he said in an interview published in the British newspaper on Friday.

Tusk said a potential Russian attac...