President Donald Trump has called for the US to retake control of the Panama Canal unless the cost of passage for naval and merchant ships is slashed. Trump’s refusal to rule out the use of force is a throwback to the 19th century era of gunboat diplomacy.

Doubling down on his pre-inauguration threat to reimpose U.S. control over the canal, Trump, in his inauguration speech Monday, again accused Panama of breaking the promises it made for the final transfer of the strategic waterway in 1999 and of ceding its operation to China — claims that Panama has vehemently denied.

U.S. President Donald Trump’s insistence that he wants to have the Panama Canal back under U.S. control is feeding nationalist sentiment and worry in Panama, home to the critical trade route and a country familiar with U.