And now that Russia was plunging deeper into its own confrontation with the United States, Mr. Raisi told Mr. Putin in televised remarks, it was time to take on “the power of the Americans with an increased synergy between our two countries.”

It was a bit of geopolitical theater at the Kremlin at a critical moment for Washington and its adversaries. Mr. Raisi, the hard-line Iranian leader, started a two-day trip to Moscow on Wednesday designed to showcase tightening bonds between two countries with often-diverging interests and a history of strained relations — but, increasingly, along with China, a single adversary: the United States.

For Mr. Putin, embroiled in a dispute with the United States over spheres of influence and facing harsh sanctions if he follows through on a threatened invasion of Ukraine, it was a chance to show that Russia has friends it can call on in its battles with the West. In keeping with that message, the visit will include an address by Mr. Raisi to Russia’s lower house of Parliament, a rare honor for a visiting leader.