Russia has started to prepare for war with Poland, the country’s military chief has said, in comments that echo warnings by European leaders about Moscow’s intentions post-Ukraine. General Staff of the Polish Armed Forces,

Some of America's closest European allies say they're already in a gray zone between peace and war with Russia.

Russia has capacity for a limited attack against NATO territory at any time but a decision to act would depend on the Western allies' posture, a top German military official warned.

"If you look at Russia's current capabilities and combat power, Russia could kick off a small-scale attack against NATO territory as early as tomorrow," Lieutenant General Alexander Sollfrank, head of the NATO ally's joint operations command, told Reuters.

Poland has scrambled fighter jets just hours after a top general warned Russia is preparing for war against NATO. The Eastern European country's Armed Forces posted on social media details of "preventative" actions taken overnight to secure airspace in parts of Poland close to regions in Ukraine under attack from Russia.

Military capability of Western alliance remains 'formidable' despite questions around US commitment to untested 'mutual assistance' agreement

Professor Michael Clarke has been answering your Ukraine war questions live - scroll down for the best of his answers, or use the video below to watch back this week's Q&A.

The Polish government said it believes that Russian secret services are behind the bombing of a major railway line in the NATO country, in what Prime Minister Donald Tusk described as an “unprecedented act of sabotage".