London (CNN) US President Donald Trump is trying to "make an example" of Julian Assange, the WikiLeaks founder's defense team argued in a London court Monday at the start of his extradition hearing.

By publishing a trove of classified defense documents relating to Iraq and Afghanistan, Assange had revealed evidence of war crimes, his legal team said.

Lawyers for the US government argued that by publishing the diplomatic cables in an unredacted form, Assange had put the lives of sources and informants in "immediate" danger, and damaged the capabilities of US forces carrying out operations abroad,

Assange, 48, was arrested on a US extradition warrant in April last year at the Ecuadorian embassy in London, where he had lived since claiming asylum there in 2012.

He faces 18 charges in the US for his alleged role in encouraging, receiving and publishing classified documents linked to national defense. If convicted, he could be sentenced to up to 175 years in jail.

Counsel for the US government, James Lewis, told Woolwich Crown Court, that Assange could not use journalism as an excuse for hacking. "Reporting or journalism is not a license for criminality," Lewis told the court. In any case, Assange was not entitled claim a journalism defense, as he was not a journalist, Lewis argued.

Lewis said Assange had previously conceded that the publication of names was regrettable. But the lawyer said that "what is alleged is far more than regrettable -- it's criminal."

Lewis told the court that the charges against Assange were not linked to his publication of evidence of any war crimes, but instead related to "publishing specific classified documents that contained unredacted names of innocent people who risked their safety and freedom to aid United States and its allies."

Supporters Julian Assange outside Woolwich Crown Court on Monday.

Representing Assange, lawyer Edward Fitzgerald said asking for extradition on the basis of what was "clearly" a political case was an abuse of the court's process.

"Julian Assange is being made an example of. President Trump and his administration decided to make an example of Julian Assange," Fitzgerald said, adding that Assange's actions had brought evidence of war crimes to public attention.

At a preliminary hearing last week, Fitzgerald said that former US congressman Dana Rohrabacher had offered the WikiLeaks founder a pardon on behalf of President Trump, in exchange for denying Russian involvement in the leak of emails from the Democratic National Committee in 2016. Wikileaks published the emails in July that year.

The White House and Rohrabacher have strongly denied that Trump intervened in Assange's case. Rohrabacher has previously said the visit was "my own fact finding mission," and claimed he had never spoken to Trump about Assange. White House Press Secretary Stephanie Grisham dismissed Fitzgerald's claim as "a total lie."

On Monday, Fitzgerald told the court that Rohrabacher had approached Assange in the Ecuadorian embassy and discussed a "preemptive pardon."

The former congressman was accompanied on the visit by controversial conservative blogger Charles "Chuck" Johnson . The pair made it clear that they were acting on behalf of the President, who had approved of the meeting, Fitzgerald said.

Assange's defense team said Rohrbacher presented what he called a "win-win" solution, whereby Assange could identify the source of the DNC hack in return for a pardon.

Assange did not identify the source, Fitzgerald said.

John Shipton, father of Julian Assange, speaks to media outside at Belmarsh prison prior to his son's extradition hearing.

Assange's father John Shipton and WikiLeaks editor-in-chief Kristinn Hrafnsson were in the public gallery for the start of the extradition hearing on Monday.

Chants of "no extradition" from the crowd of Assange supporters gathered outside could be clearly heard inside the courtroom.

During Monday's proceedings, judge Vanessa Baraitser asked counsel to pass a message to the protesters outside, warning them they risked harming the case because journalists -- especially those who didn't make it into the courtroom -- were struggling to hear the proceedings.

"I'm having difficulty concentrating, this noise is not helpful either," said Assange, who appeared in court wearing a gray suit, white shirt and gray sweater.

"I'm very appreciative of the public support and understand they must be disgusted by these proceedings," he added.

Photos: WikiLeaks founder Julian Assange WikiLeaks founder Julian Assange speaks to the media from the balcony of the Ecuadorian Embassy in London in May 2017. Assange, founder of the website WikiLeaks, has been a key figure in major leaks of classified government documents, cables and videos. Hide Caption 1 of 22 Photos: WikiLeaks founder Julian Assange Assange holds a copy of The Guardian newspaper in London on July 26, 2010, a day after WikiLeaks posted more than 90,000 classified documents related to the Afghanistan War. Hide Caption 2 of 22 Photos: WikiLeaks founder Julian Assange Assange attends a seminar at the Swedish Trade Union Confederation in Stockholm on August 14, 2010. Six days later, Swedish prosecutors issued a warrant for his arrest based on allegations of sexual assault from two women. Assange has always denied wrongdoing. Hide Caption 3 of 22 Photos: WikiLeaks founder Julian Assange Assange, in London, displays a page from WikiLeaks on October 23, 2010. The day before, WikiLeaks released approximately 400,000 classified military documents from the Iraq War. Hide Caption 4 of 22 Photos: WikiLeaks founder Julian Assange Assange and his bodyguards are seen after a news conference in Geneva, Switzerland, in November 2010. It was the month WikiLeaks began releasing diplomatic cables from US embassies. Hide Caption 5 of 22 Photos: WikiLeaks founder Julian Assange Assange sits behind the tinted window of a police vehicle in London on December 14, 2010. Assange had turned himself in to London authorities on December 7 and was released on bail and put on house arrest on December 16. In February 2011, a judge ruled in support of Assange's extradition to Sweden. Assange's lawyers filed an appeal. Hide Caption 6 of 22 Photos: WikiLeaks founder Julian Assange In October 2011, a month after WikiLeaks released more than 250,000 US diplomatic cables, Assange speaks to demonstrators from the steps of St. Paul's Cathedral in London. Hide Caption 7 of 22 Photos: WikiLeaks founder Julian Assange Assange leaves the High Court in London in December 2011. He was taking his extradition case to the British Supreme Court. Hide Caption 8 of 22 Photos: WikiLeaks founder Julian Assange Assange leaves the Supreme Court in February 2012. In May of that year, the court denied his appeal against extradition. Hide Caption 9 of 22 Photos: WikiLeaks founder Julian Assange Assange addresses the media and his supporters from the balcony of the Ecuadorian Embassy in London on August 19, 2012. A few days earlier, Ecuador announced that it had granted asylum to Assange. In his public address, Assange demanded that the United States drop its "witch hunt" against WikiLeaks. Hide Caption 10 of 22 Photos: WikiLeaks founder Julian Assange Assange speaks from a window of the Ecuadorian Embassy in December 2012. Hide Caption 11 of 22 Photos: WikiLeaks founder Julian Assange Assange addresses the Oxford Union Society from the Ecuadorian Embassy in January 2013. Hide Caption 12 of 22 Photos: WikiLeaks founder Julian Assange Assange appears with Ecuadorian Foreign Minister Ricardo Patino on the balcony of the embassy in June 2013. Hide Caption 13 of 22 Photos: WikiLeaks founder Julian Assange Assange speaks during a panel discussion at the South By Southwest Festival in Austin, Texas, in March 2014. Hide Caption 14 of 22 Photos: WikiLeaks founder Julian Assange Assange attends a news conference inside the Ecuadorian Embassy in London in August 2014. Hide Caption 15 of 22 Photos: WikiLeaks founder Julian Assange Assange is seen on a video screen in March 2015, during an event on the sideline of a United Nations Human Rights Council session. Hide Caption 16 of 22 Photos: WikiLeaks founder Julian Assange Assange, on the balcony of the Ecuadorian Embassy, holds up a United Nations report in February 2016. The United Nations Working Group on Arbitrary Detention said that Assange was being arbitrarily detained by the governments of Sweden and the United Kingdom. Hide Caption 17 of 22 Photos: WikiLeaks founder Julian Assange Assange speaks to the media in May 2017, after Swedish prosecutors had dropped their investigation of rape allegations against Assange. But Assange acknowledged he was unlikely to walk out of the embassy any time soon. "The UK has said it will arrest me regardless," he said. "The US CIA Director (Mike) Pompeo and the US attorney general have said that I and other WikiLeaks staff have no ... First Amendment rights, that my arrest and the arrest (of) my other staff is a priority. That is not acceptable." Hide Caption 18 of 22 Photos: WikiLeaks founder Julian Assange Assange was seen for the first time in months during a hearing via teleconference in Quito, Ecuador, in October 2018. The hearing was then postponed due to translation difficulties. Hide Caption 19 of 22 Photos: WikiLeaks founder Julian Assange A van displays images of Assange and Chelsea Manning, the former Army intelligence analyst who supplied thousands of classified documents to WikiLeaks, outside the Ecuadorian Embassy in London on Friday, April 5. A senior Ecuadorian official said no decision has been made to expel Assange from the embassy. According to WikiLeaks tweets, sources had told the organization that Assange could be kicked out of the embassy within "hours to days." Hide Caption 20 of 22 Photos: WikiLeaks founder Julian Assange A screen grab from video footage shows the dramatic moment when Assange was hauled out of the Ecuadorian Embassy by police on Thursday, April 11. Assange was arrested for "failing to surrender to the court" over a warrant issued in 2012. Officers made the initial move to detain Arrange after Ecuador withdrew his asylum and invited authorities into the embassy, citing the Australian's bad behavior. Hide Caption 21 of 22 Photos: WikiLeaks founder Julian Assange Assange gestures from a police vehicle on his arrival at Westminster Magistrates' Court in London on April 11. US authorities have also issued an extradition warrant for Assange. The US Department of Justice confirmed Assange has been indicted on conspiracy with Manning. Hide Caption 22 of 22

The extradition hearing is expected to last several weeks.

Assange, an Australian citizen, has been held at London's high-security Belmarsh prison since his arrest.