LONDON — Making her first overseas visit since becoming Britain’s prime minister, Liz Truss used her speech at the United Nations on Wednesday to urge support for Ukraine, underscore her commitment to free-market economics and warn of the threat to global security posed by authoritarian states.
Ms. Truss succeeded Boris Johnson as prime minister this month, but the death of Queen Elizabeth II took over the agenda in Britain just days after she took power, culminating in a state funeral on Monday.
While she served as foreign secretary under Mr. Johnson, Ms. Truss’s appearance at the United Nations was her first opportunity to outline her own policies on the international stage.
She promised to lead a “new Britain” for the new era the country was entering under King Charles III, marked by a “commitment to hope and progress.”
On Ukraine, she signaled that she would continue Mr. Johnson’s policy of offering strong support for the country and its president, Volodymyr Zelensky. “We will not rest until Ukraine prevails,” she said.
And she restated a promise to raise Britain’s spending on defense to 3 percent of gross domestic product by 2030, a commitment long urged by the United States, to counter threats to European security like Russia’s invasion of Ukraine.
“This is a decisive moment in our history, in the history of this organization, and in the history of freedom,” Ms. Truss added.
“The story of 2022 could have been that of an authoritarian state rolling its tanks over the border of a peaceful neighbor and subjugating its people. Instead, it is the story of freedom fighting back.”
Ms. Truss plans to invest in Britain’s strategic capabilities and strengthen its alliances to counter authoritarian powers like Russia and China, her office said.
At home, Ms. Truss plans tax reductions that she hopes will ignite economic growth and prevent a looming recession. She said in New York that democracies working together should protect one another’s economic security in a new era of “strategic cooperation,” freeing countries from dependence “on those who seek to weaponize the global economy.”
Ms. Truss is also scheduled to meet President Biden, who will urge her to work with the European Union to resolve tensions around post-Brexit trading arrangements in Northern Ireland, the White House has said. Ms. Truss has said she will push through a bill that would allow her to change those trading rules despite her critics’ fears that this could break an international treaty and undermine the peace process that ended decades of sectarian violence in Northern Ireland.