GENEVA — Buoyed by days of partnership-building sessions with America’s democratic allies, Joe Biden arrived in Geneva on Tuesday for the most-watched and tensest part of his first European tour as president: talks with Russia’s Vladimir Putin.

Biden is seeking to restore European ties that were strained under former President Donald Trump, who dismissed the value of NATO and other longstanding U.S. alliances and sought out Putin and other autocrats. Biden this week has held long days of meetings with global leaders at the Group of Seven, NATO and U.S.-E.U. summits, where he secured joint communiques expressing concern over Russia and China, and on Tuesday helped preside over a breakthrough agreement easing a long-running U.S. trade dispute with Europe.

But Biden’s meeting today with the Russian president is his most highly anticipated.

Biden has called Putin a “worthy adversary” and has said he is hoping to find areas of cooperation with the Russian president. But he’s also warned that if Russia continues its cyberattacks and other aggressive acts towards the U.S. “we will respond in kind.”

According to a senior administration official granted anonymity to disclose internal discussions, Biden is hoping to find small areas of agreement with the Russian president, including potentially returning ambassadors back to Washington and Moscow. Both countries have been without a senior diplomat for months.

Biden is also looking to make progress on a new arms control agreement between the two nations, after Russia agreed to a five-year extension of the current agreement in January. And Biden plans to raise issues ranging from cyberattacks to Russia’s alleged involvement in air piracy, as well as Putin’s treatment of Russian opposition leader Alexei Navalny, who was jailed and poisoned in an act seen as political retribution against him for speaking out against the Russian president.