U.S. Defense Secretary Jim Mattis and the outgoing commander of U.S. Southern Command on Monday praised the recent decision to send a U.S. Navy hospital ship to aid Venezuelan refugees, warning that moves by China and Russia in the hemisphere should not be trusted.

"There is nothing more indicative of U.S. commitment to regional stability and bolstering of people-to-people ties than the USNS Comfort's mission to aid Venezuelan refugees fleeing their crisis-racked nation," Mattis said at the Southern Command ceremony.

"Alongside 10 partner nations and six non-governmental organizations, we are sending doctors, not bombers, to help limit human suffering," he added as he oversaw the change of command from outgoing Navy Adm. Kurt Tidd to Adm. Craig Faller.

Medical teams from the Comfort, which arrived at Colombia's northwestern port city of Turbo in mid-November, will provide aid to Venezuelan refugees. About three million Venezuelans have fled political turmoil and economic hardship. Roughly a million refugees have migrated to Colombia.

Southern Command has described the mission as a show of friendship, but the move may have also increased tensions in the region with China, which deployed its own hospital ship to Venezuela in September, The Guardian newspaper reported.

"China is doing everything in its power to entice nations in this hemisphere to put on a constricting belt and head down a one-way road that is primarily designed to support China's rise," Tidd said during the ceremony.

Meanwhile, Russia continues to support the most oppressive governments, such as Nicaragua and Venezuela, he added.

"While we deploy hospital ships to the region, watch them as they deploy nuclear-capable, strategic bombers and fly around the Caribbean in a show of force. Our hemisphere has no need for such patently hollow demonstrations," Tidd said.

In May, U.S. Air Force F-22 stealth fighter jets intercepted two Russian nuclear-capable bombers flying off the coast of Alaska.

"Neither Russia nor China genuinely have this region's best interest at heart. My parting advice to you, my friends -- they should be distrusted. Latin America and Caribbean states know that, in the long run, our connections to one another will always and inevitably bear the finest fruit."

-- Matthew Cox can be reached at matthew.cox@military.com.