Rouhani, for his part, denounced the "illegal" U.S. withdrawal from the global nuclear deal with Tehran.
"Now all these loading and unloading operations of military equipment and personnel are no longer needed".
"For our country, it's a great joy and honor to receive representatives from the massive footballing family, " Putin said in a video statement released Saturday.
A spokesman for Prime Minister Justin Trudeau said that Ottawa's position against such a move had not changed with regards to Russian Federation.
"I see this as an acknowledgement and an evaluation of Russia's efforts to develop a comprehensive strategic partnership with China", he said. "We are facing a very volatile region", she said.
G7 leaders demanded that Russian Federation stop what they described as attempts to undermine democracy.
Putin said he shared Trump's concern about a renewed arms race expressed in a March phone call.
Since the heads of state of China, Russia and Mongolia held their first meeting more than three years ago, the three countries have centered on aligning China's Belt and Road Initiative with Russia's development strategies, especially its transcontinental rail plan, and Mongolia's "development path" initiative, deepened cooperation and yielded results, said Xi.
He emphasised that the bloc's members, who also include China, four ex-Soviet Central Asian nations, as well as India and Pakistan, are anxious about the USA move.
The Russian President stated that U.S. leader Donald Trump in their latest conversation expressed concern about a new round of the arms race.
Xi, whose government is locked in tough negotiations with the United States to avoid a trade war, said World Trade Organisation rules and the multilateral trading system should be upheld to build an open world economy.
On Friday, Trump shocked USA allies by calling for Russian Federation to be readmitted to the Group of Seven wealthy industrialized nations.
Iranian President Hassan Rouhani on Sunday criticized USA "unliteralism" in withdrawing from the Iran nuclear deal and said he appreciated efforts by China and Russian Federation to maintain the agreement.
Rouhani said the U.S. was monitoring the global reaction to its withdrawal from the nuclear deal, and a weak response would encourage it to carry on acting unilaterally.
Tension has been building over a year of policymaking that has distanced the U.S. from traditional allies, including by Trump's decisions to withdraw the United States from the Paris climate accord and the Iran nuclear agreement.