The Polish foreign ministry said in a social media post that the two met in the Polish capital on Tuesday.
The US ambassador to Warsaw, Mark Brzezinski, who also attended the meeting, shared that the talks revolved around "ways of expanding future cooperation and our common priorities in areas including Ukraine."
"Poland is an irreplaceable ally, partner and friend of the United States," Brzezinski said in his post.
He added: "Our cooperation with the new Polish government and the Polish people will continue to develop and strengthen our bilateral relations."
While in Warsaw on Tuesday, O'Brien also met with Jacek Siewiera, head of Polish President Andrzej Duda's National Security Bureau (BBN).
The BBN said on the X platform that Siewiera and O'Brien discussed "support for Ukraine in the ongoing war with Russia and preparations for a NATO summit in Washington."
The US Department of State said in a statement that O’Brien on Monday visited the Ukrainian capital Kyiv, "where he met with Ukrainian Presidential Office Head Andriy Yermak, Minister of Defense Rustem Umerov, Minister of Digital Transformation Mykhailo Fedorov, and Minister of Reconstruction Oleksandr Kubrakov to discuss preparations for winter, economic recovery efforts, and to reiterate enduring U.S. support in the face of Russia’s aggression."
The statement said that O’Brien's trip to Warsaw included meetings with senior officials in the newly formed Polish government "to build upon our already strong bilateral relationship and discuss our continued support for Ukraine."
Russia invaded Ukraine on February 24, 2022, launching the largest military campaign in Europe since World War II.
Wednesday is day 665 of Russia’s war on Ukraine.
(gs)
Source: PAP, state.gov