The US President and his Russian counterpart met in Helsinki to discuss a wide array of issues, including bilateral relations between the two countries, their cooperation in Syria and alleged Russian meddling in the 2016 US presidential election.

Former CIA Director John Brennan slammed US President Trump's "performance" during the press conference after his meeting with Putin in Helsinki as "treasonous" on his Twitter. He also claimed that Trump is "in the pocket" of Russian President Vladimir Putin and said that he had exceeded the "threshold of high crimes and misdemeanors."

Donald Trump’s press conference performance in Helsinki rises to & exceeds the threshold of “high crimes & misdemeanors.” It was nothing short of treasonous. Not only were Trump’s comments imbecilic, he is wholly in the pocket of Putin. Republican Patriots: Where are you??? — John O. Brennan (@JohnBrennan) July 16, 2018

He also expressed skepticism as to why the two presidents discussed matters in private, stating that Trump lacks credibility and is probably hiding something from his advisers.

Why did Trump meet 1 on 1 with Putin? What might he be hiding from Bolton, Pompeo, Kelly, & the American public? How will Putin use whatever Trump could be hiding to advantage Russia & hurt America? Trump’s total lack of credibility renders spurious whatever explanation he gives. — John O. Brennan (@JohnBrennan) July 16, 2018

Brennan also called on Trump's team to resign in protest against his "performance" in Helsinki on July 16, saying that no "good American patriot" would stay with Trump after that.

"He criticized American citizens, Secretary Clinton, and others as opposed to really taking advantage of a world stage with all the world's eyes upon them to point out how unacceptable Russia's behavior and interference in our election […] But he just shirked those responsibilities," Brennan said.

A number of other US officials have also scolded the US president's press conference in Helsinki. US Senator John McCain added to the wave of accusations that Trump's performance at the press conference with Putin was "a tragic mistake." He also slammed the US president for failing "to defend America."

"Not only did President Trump fail to speak the truth about an adversary; but speaking for America to the world, our president failed to defend all that makes us who we are — a republic of free people dedicated to the cause of liberty at home and abroad," McCain wrote on his website.

Former US Ambassador to Moscow Michael McFaul, a strong Kremlin critic banned from Russia over harming bilateral ties, mocked Trump's statements in which he said that the US has been to blame for deteriorating relations between America and Russia. McFaul suggested that Trump should have blamed Moscow instead.

"For President Trump to just insinuate as he just did in his initial remarks today, well bygones — let's forget about all that stuff and move on because I want a great relationship with you, Putin. That's just not serving America's national interest, in my view," former envoy said.

Democrat Senator Jeff Merkley suggested in an interview with BuzzFeed News that Moscow is "likely" to have compromising material on Trump, claiming that it is a "standard strategy of Russia" for important visitors to the country. He further speculated that Moscow might have the so called "pee tape" allegedly depicting Trump ordering two prostitutes to urinate on a bed in at the Moscow Ritz-Carlton, where Obama's family once stayed.

READ MORE: Putin, Trump Consider Joint Summit 'Success,' Denounce 'Collusion' Claims

US Senator Lindsey Graham slammed Trumps speech at the press conference by saying that it was a "missed opportunity" to hold Russia accountable for the alleged meddling in the 2016 election. He further claimed that the speech will be seen as a sign of weakness in Kremlin, going on to suggest that Trump should check the soccer ball that Putin gave him during the conference to see if it is wired.

Finally, if it were me, I’d check the soccer ball for listening devices and never allow it in the White House. — Lindsey Graham (@LindseyGrahamSC) July 16, 2018

US Republican Senator Bob Corker said in a comment regarding the Helsinki summit that he wants the US to improve relations with Russia, but added that Trump should have been more forceful when he addressed issues with Putin.

US House Minority Leader Nancy Pelosi criticized Trump for not confronting Putin in regards to alleged Russian meddling in the presidential election, days after the Justice Department accused 12 Russian intelligence officers of involvement in the interference.

READ MORE: 'US Needs Russia More Than Russia Needs US' — Academic on Trump-Putin Summit

US President Donald Trump and his Russian counterpart Vladimir Putin met in Helsinki on July 16 and discussed an array of international issues, including the countries' bilateral relations. The two presidents called the meeting highly "successful" and "productive," saying that it was just the first step.

Trump and Putin agreed to enhance their cooperation in Syria, particularly regarding the delivery of humanitarian aid and securing the Israeli-Syrian border. Both presidents also pledged to continue the ongoing cooperation between their armed forces in Syria and on preventing terrorist attacks.

READ MORE: LIVE UPDATES: Putin, Trump Hold First Ever One-on-One Summit in Helsinki

The two leaders also discussed the alleged Russian meddling in the US presidential elections. During the press conference, Putin assured that Moscow had not colluded with Trump's election campaign and would never intervene in the US electoral process.

Trump said that Russia had "zero reasons" to meddle in the elections and said that his victory was due to his "brilliant" campaign. The US president also scolded the Democratic Party and Hillary Clinton for fueling special counsel Mueller's investigation into the alleged meddling, saying that it has negatively affected US-Russian relations.