During a visit to Panama, Hegseth suggested that "by invitation" the United States could "revive" military bases or naval air stations and rotate deployments of US troops to an isthmus the United States invaded 35 years ago.

Since coming to power in January, President Donald Trump has claimed that China has too much influence over the canal, which handles about 40 percent of US container traffic and five percent of world trade.

His administration has also vowed to "take back" control of the interoceanic waterway that the US funded, built and controlled until 1999.

Hegseth on Wednesday suggested the slew of former US military bases that dot Panama could again be used to host US troops.

He said a deal signed deal with Panama this week was an "opportunity to revive, whether it's the military base, naval air station, locations where US troops can work with Panamanian troops to enhance capabilities and cooperate in a rotational way."

Hegseth cited the possibility of "joint exercises" but the mention of a "rotational" force is likely to raise the hackles of Panamanians, for whom sole ownership of the canal is a source of intense national pride.

The US has long participated in military exercises in Panama, but a longer-term rotational force -- like the one the US maintains in Darwin, Australia -- would be politically toxic for Panama's center-right leader Jose Raul Mulino.