TEHRAN (Press Shia Agency) – Chinese President Xi Jinping treated Russian counterpart Vladimir Putin to a state visit on Friday as the neighboring giants forge closer ties in the face of US diplomatic and economic challenges.

Putin, re-elected to his fourth Kremlin term in March, arrived at the grandiose Great Hall of the People in Beijing for talks with Xi, who could stay in power for life after term limits were lifted this year, AFP reported.

The two heads of state reviewed a military honor guard and greeted flag-waving children during the welcoming ceremony before retreating into the vast building.

The most powerful Russian and Chinese leaders in decades, Xi and Putin have built closer ties while US President Donald Trump has labeled both countries as economic rivals that challenge US interests and values.

China is mired in tough negotiations with the United States to avoid a trade war, while Moscow has deep differences with Washington on multiple diplomatic fronts, including Syria and Ukraine.

Putin played up his bond with his "good friend" Xi in an interview with China's state broadcaster CGTN this week.

He said the Chinese president was the only state leader to celebrate his birthday with him. 

Xi "is approachable and sincere", Putin told CGTN. "But he's also a very dependable man to work with."

After the Beijing visit, Putin will join Xi at a weekend summit of the Shanghai Cooperation Organization (SCO) in the eastern Chinese city of Qingdao.

China and Russia lead the regional security group, which includes former Soviet states and new members India and Pakistan.

Putin told CGTN that the SCO had "small" objectives when it was founded two decades ago but that it was now evolving into a larger global force.

Iranian President Hassan Rouhani, whose country is an observer member of the SCO, will also attend the summit at a time when China and Russia are seeking to save the Iran nuclear deal following Trump's withdrawal from the pact.