During his first term in office, U.S. President Donald Trump applied his particular brand of diplomacy with Washington¡¯s adversaries, publicly befriending Russia and North Korea while separately piling pressure on China and Iran.

This time he faces a different kind of challenge: a more united group of U.S. antagonists who have drawn closer following Russia¡¯s 2022 invasion of Ukraine.

Trump, who took office Monday, has vowed to end Russia¡¯s war in Ukraine, curb Iran¡¯s nuclear program and counter China while building up the U.S. military.