Final answer:
President Polk provoked the war to settle the Texas-Mexico border dispute.
Step-by-step explanation:
President Polk provoked a war between the United States and Mexico to settle the dispute over the Texas-Mexico border. The U.S. claimed that the border was at the Rio Grande, while Mexico believed it was at the Nueces River. Polk sent troops to the disputed area, leading to a clash and eventually the Mexican-American War.
Learn more about reasons behind the U.S.-Mexico war