Allen, a 31-year-old from California, was also charged with weapon offences relating to the incident at the Washington DC Hilton. He did not enter a plea BBC reported.
Donald Trump is "satisfied" with the Secret Service response to Saturday's shooting at the press dinner, the White House said
But Press Secretary Karoline Leavitt did not rule out possible changes to security protocols, with a meeting to take place this week reviewing presidential security
In an interview after the shooting, Trump said: "I wasn't worried. I understand life. We live in a crazy world"
A lot has happened today in the aftermath of Saturday's shooting at the White House Correspondents' Dinner.
The suspected gunman, Cole Tomas Allen, appeared in court for the first time as Trump administration officials tried to paint a clearer picture of what allegedly happened at the Hilton hotel that night.
Here are a few key takeaways from the day:
The 31-year-old suspect appeared before a judge in a Washington DC federal court
He faces three charges, the most serious of which is attempting to assassinate the president. It could carry a life sentence if he is convicted.
Allen did not enter a plea today, and his next appearance is on Thursday
More charges may be coming, officials said
Justice Department leaders spoke about Allen's alleged plans for the shooting, including photos of knives and guns they say Allen carried with him and an email they describe as a "manifesto"
But they say a more specific motive is not clear yet
Officials have also stressed that security protocols at the event worked, but the White House said today they are not ruling out changes to the president's security
Meanwhile, both the president and Melania Trump have taken aim at Jimmy Kimmel for a joke he made last week, calling the first lady an "expectant widow"
