President Barack Obama has announced plans for a $1bn (£600m) fund to increase US military deployments to Europe, during a visit to Poland.
Mr Obama, who will meet Nato leaders amid concerns over the Ukraine crisis, said the security of America's European allies was "sacrosanct".
In April, 150 US soldiers were sent to Poland for military exercises amid growing tensions with Russia.
Mr Obama will also visit Belgium and France during his tour. READ MORE OF THIS STORY