SAN JUAN, Puerto Rico — U.S. Defense Secretary Pete Hegseth and Air Force Gen. Dan Caine, chairman of the Joint Chiefs of Staff, arrived in Puerto Rico on Monday for an unexpected visit as the U.S. steps up its military operations against drug cartels in the Caribbean.

Their arrival in the U.S. territory comes more than a week after ships carrying hundreds of U.S. Marines deployed to Puerto Rico for what officials said was a training exercise, a move that some on the island have criticized.

But on Monday night, Hegseth said in a video posted on X that the deployed Marines were “on the front lines of defending the American homeland.”

“Make no mistake about it, what you’re doing right now is not training. This is the real-world exercise on behalf of the vital national interest of the United States of America to end the poisoning of the American people,” he said while aboard the USS Iwo Jima.

Earlier in the day, Puerto Rico’s Gov. Jenniffer Gonzalez said Hegseth and Caine visited on behalf of President Donald Trump’s administration to support those participating in the training.

“We thank President Trump and his administration for recognizing the strategic importance of Puerto Rico to U.S. national security and for their fight against drug cartels and the narco-dictator Nicolas Maduro,” Gonzalez said.

Hegseth and Caine met with officials at the 156th Wing Muniz Air National Guard Base in Carolina, a city just east of the capital of San Juan.

Gonzalez said Hegseth spoke to nearly 300 soldiers at the base and thanked those he described as “American warriors” for their work. He later departed for the USS Iwo Jima.