The United States has offered Ukraine security guarantees similar to those in NATO's "Article 5" but without requiring the country to join the defense alliance, a diplomatic source told AFP news agency. That article stipulates that NATO members will consider an attack on any one of them as an attack on the entire alliance, and its implementation could mean sending military forces from member states to assist the attacked country. At the same time, the source noted that the American offer depends on "prior agreement from Russian President Vladimir Putin."