Fearful or Cheerful? World Leaders Mull a Potential Trump Foreign Policy

They promised a harder line against China.

They assailed President Biden’s withdrawal from Afghanistan.

They attributed the conflicts in Ukraine and Israel to American weakness, pledged a crackdown on undocumented immigrants and vowed to end “free rides” for American allies.

The lineup of speakers at the Republican National Convention on Wednesday sketched out a vision for American foreign policy that leans harder into former President Donald J. Trump’s populist and isolationist instincts and further jettisons long-held Republican views.

The rest of the world was watching.

For months, officials around the globe have weighed the possibility of Mr. Trump’s return to the White House. In Buenos Aires, Riyadh and Budapest, leaders could be expected to welcome it. In London, Seoul and Berlin, it would likely further test faith in American dependability. And in Mexico City, Kyiv and Beijing, leaders appear to be steeling themselves for potential upheaval and further ruptures.

Already, with Mr. Trump consistently polling ahead of Mr. Biden, some governments are taking concrete steps to prepare for the former president’s possible return.

South Korea is racing to finalize a deal with Washington on sharing the costs of keeping U.S. troops in the country, anticipating Mr. Trump will demand that Seoul pay more. Mexico is studying how to protect millions of its citizens who might be deported from the United States.