Rubio said he reinforced President Donald Trump's disappointment that there has not been more flexibility on the Russian side.

"We need to see a roadmap moving forward about how this conflict can conclude," Rubio said after the 50-minute meeting on the sidelines of the ASEAN conference.

The meeting was their second face-to-face encounter since Rubio took office, although they have spoken by phone several times. Their first meeting came in February in Riyadh, Saudi Arabia, as the Trump administration sought to test both Russia and Ukraine on their willingness to make peace.

This one occurred shortly after the U.S. resumed some shipments of defensive weapons to Ukraine following a pause — ostensibly for the Pentagon to review domestic munitions stocks — that was cheered in Moscow.

The resumption comes as Russia fires escalating air attacks on Ukraine and as President Donald Trump has become increasingly frustrated with Russian President Vladimir Putin.

"Putin is not, he's not treating human beings right," Trump said during a Cabinet meeting Tuesday, explaining the pause's reversal. "It's killing too many people. So we're sending some defensive weapons to Ukraine, and I've approved that."

Rubio was also seeing other foreign ministers, including many whose countries face tariffs set to be imposed on Aug. 1. The tariff threat could overshadow the top diplomat's first official trip to Asia, just as the U.S. seeks to boost relations with Indo-Pacific nations to counter China's growing influence in the region.