VATICAN CITY — Pope Francis encouraged Russian President Vladimir Putin to engage in “sincere” international efforts aimed at bringing peace to Ukraine as the two men met privately at the Vatican Wednesday.

Earlier in the day, the U.S. ambassador to the Holy See, Kenneth Hackett, said his country would like to see the Vatican step up its concern about what is happening in Ukraine during the pope’s meeting with Putin, the second time the Russian leader and Francis have met since the pontiff was elected in 2013.

While Francis has deplored the loss of life in Ukraine and called on all sides to respect what has proven to be a shaky cease-fire, he hasn’t publicly put any blame on Russia in an apparent bid not to upset the Holy See’s often thorny relations with the Orthodox Church in Russia, where Catholics are a tiny minority.

“We think they could say something more about concern of territorial integrity, those types of issues,” Hackett told reporters. “It does seem that Russia is supporting the insurgents. And it does seem that there are Russian troops inside Ukraine.”

During the few minutes that Putin and Francis greeted each other and took their leave before and after their 50-minute-long closed door talks, there was no mention of any blame regarding Ukraine, although the protracted hostilities in that Eastern European nation was a main thrust of the discussion.

“As it was possible to predict in the context of the world situation, the talks were dedicated principally to the conflict in Ukraine and the situation in the Middle East,” said a Vatican spokesman, the Rev. Federico Lombardi.

The Holy See is highly worried about the fate of the Christian minority in the Middle East.

Putin and Francis seemed eager to start their talks, which began quite tardily. Putin arrived an hour and 20 minutes late, after flying to Rome from Milan.

Despite Putin’s delay, a rare breach of protocol for VIPs paying a call on the pope, Francis greeted him cordially in German, a language the Russian knows well from his secret service days.

In their talks about Ukraine, Lombardi said, Francis stressed the “need to commit oneself in a sincere and great effort to achieve peace.” Lombardi said both men “agreed on the importance of reconstructing a climate of dialogue and that all sides commit oneself to implementing the Minsk accords.”

Francis also stressed that all sides work toward easing the tensions in the regions.

As he has done with other VIP visitors, the pontiff presented Putin with a medallion depicting an “angel of peace.”