U.S. President Joe Biden called Qatar's Emir Sheikh Tamim bin Hamad al-Thani to thank him for Doha's mediation that resulted in the release of a number of Americans from Iran, the Amiri Diwan and the White House said on Tuesday.
Last month, with Doha's mediation, Iran freed five Americans as part of a prisoner swap for five Iranians held in the United States and the transfer of $6 billion in Iranian funds, marking a rare deal between the long-time antagonists.
Qatar, a wealthy Gulf Arab state with diplomatic ambitions, has both Washington and Tehran to engage in more talks and reach "understandings", sources told Reuters last month.
"During the call, the strategic relations between the two countries and aspects of supporting and strengthening them in various fields were reviewed", the Amiri Diwan, or Emir's office, said in a statement.
The White House said the two leaders "discussed their commitment to deepen defense and security cooperation in the region".
Last year, Biden designated Qatar as a major non-NATO ally of the United States, fulfilling an earlier promise that he had made to them.
The designation is granted by the United States to close, non-NATO allies that have strategic working relationships with the U.S. military.
Qatar has recently held separate bilateral meetings with the United States and Iran that touched on Iran's nuclear program and U.S. concerns about Iranian drone transfers to Russia, sources have told Reuters.