BRUSSELS — The European Union cannot rely on the United States to defend it and must increase military spending and security preparedness to help Ukraine and deter Russia from targeting any more of its neighbors, top EU officials warned on Wednesday. “Ask not of America what it can do for our security. Ask yourselves what we can do for our own security,” Polish Prime Minister Donald Tusk, whose country holds the EU presidency, said, paraphrasing a quote from U.S. President John F. Kennedy’s