A man has pleaded guilty to scrawling graffiti about Fusilier Lee Rigby's murder on the RAF Bomber Command War Memorial.
Daniel James Smith, 21, of Grecian Street North, Salford, admitted writing "Lee Rigby's killers should hang" on the memorial in central London on June 5 - a monument he did not realise was a war memorial.
Colleen Gildernew, defending, said: "He had no idea that the war memorial was a war memorial.
"He is very disgusted with himself, even more so because of that."
Smith also daubed "EDL" and "F*** the police" on the memorial in Green Park, prosecutor Izolda Switala-Gribbin said.
Smith was planning on going to Fusilier Rigby's funeral but was arrested and could not go, Westminster Magistrates' Court heard.
Ms Gildernew said Smith had applied for a job in the British Army but was unsuccessful "because of his convictions as a young boy".
The court heard Smith has 44 convictions and has appeared in different courts five times this year.
Ms Gildernew said the experiences of Smith's two army friends - one who has lost both legs and another who suffers from memory loss as the result of a bomb - had an "emotional impact on him".
The memorial was vandalised twice in just over a week following the murder of Fusilier Rigby in Woolwich, south east London, on May 22.
District Judge Quentin Purdy described the content of the graffiti inflicted on June 5 by Smith, and its location, as "highly emotive".
He added that Smith's actions clearly challenged the "tolerance we all seek to see in society".
Mr Purdy said people will want to know what the court is doing about people, "brains in gear or not", who inflict such damage.
The judge said he was prepared to explore all "reasonable options" for Smith moving on rather than being sent back into custody.
But he said a custodial sentence was a possibility, adding "there may be no alternative".
Mr Purdy told Smith his punishment should "reflect the public's concern about your criminal conduct".
He told the 21-year-old his actions "caused offence to many".
The court was told that Smith has spent the past 11 weeks in Feltham Young Offenders' Institution and was released only yesterday.
Mr Purdy said it was "slightly worrying" that Smith was released with few arrangements in place.
Smith's previous convictions relate mainly to shoplifting, Ms Gildernew told the court.
She said he was brought up by his grandmother and had little in terms of family support, describing his childhood as "unsettled".
The court heard that he left school at the age of 15 with no qualifications, battled cannabis addiction in his teenage years and struggled with homelessness.
Ms Gildernew said Smith, dressed in a colourful T-shirt, was "shaking and very tearful" before the hearing.
Smith also pleaded guilty to causing £510 of criminal damage to a wall of a commercial property in Knightsbridge.
Mr Purdy remanded Smith in custody and adjourned sentencing until Tuesday November 5 at the same court pending further inquiries into suitable arrangements for him.