Russia has released former United States Marine Robert Gilman from detention on humanitarian grounds after more than four years in custody, following concerns over his deteriorating health. US President Donald Trump announced Gilman’s release on Tuesday, saying Russia agreed to free him after discussions with Russian President Vladimir Putin. Trump said the release was “very much on a humanitarian basis” and that Russia did not ask for anyone in return, adding that “no exchange took place.” His mother, who had travelled to Russia while seeking access to her son in a prison hospital, is accompanying him on his journey home. He is among at least nine other Americans still known to be imprisoned in Russia.