Mr. Rinkevics was sworn in as president of Latvia on Saturday in Riga. He had been foreign minister since 2011.

Even though the president of Latvia is mostly a figurehead, he or she can reject laws and call for referendums.

There have been openly gay heads of government in the EU before, but there has never been a gay head of state.

In many countries, like the United States, the president and the prime minister are two different people. Elio di Rupo, who used to be the Prime Minister of Belgium, was the first openly gay head of government in the EU.

Mr. Rinkevics, who is 49 years old, first came out as gay in 2014. Since then, he has been a strong supporter of LGBT rights.

Even though gay marriage is against the law in Latvia, same-sex unions were legalized by the country’s constitutional court last year.

In the third round of votes in May, Latvia’s parliament chose Mr. Rinkevics to be the next president of the country.

In his first speech as president on Saturday, Mr. Rinkevics promised to keep helping Ukraine in its war against Russia.

He said that Latvia’s foreign policy “does not have time for mistakes” and that he will act “quickly, decisively, and wisely.”

In his message, Mr. Rinkevics also told young Latvians to “break the glass ceiling” and called inequality a “big problem.”

“The gap between rich and poor in our country is too wide,” he said.

“While I am president, I will fight for a modern and strong Latvia, a legal and fair Latvia, the well-being of the people, and a society that treats everyone with respect.

“And this is something we can all do if we all work together.”

Egils Levits, who was president for four years, is being replaced by Valdis Rinkevics. Levits will represent Latvia at the NATO meeting next week in Vilnius, Lithuania.

Latvia is one of the three Baltic states that joined the EU in 2004 after breaking away from the Soviet Union in the early 1990s. The other two Baltic states are Lithuania and Estonia.