Troop drawdowns in Africa and Latin America would go against vital U.S. national security interests, commanders said.
Members of the 13th Marine Expeditionary Unit will spend October in the U.S. Southern Command area of operations.
Roughly 600 service members participated in the Air Force's New Horizons humanitarian outreach program.
The Navy hospital ship Comfort will deploy next month to the Caribbean and Central and South America to provide assistance.
"In addition to mercenaries and Russian troops, the Kremlin has also publicly signaled its support for Maduro."
"The final phase in the collapse of South American strongmen is typically the point at which the military switches sides."
About 300 U.S. Marines and Navy sailors deployed last year to Soto Cano Air Base in Honduras.
As Russia and China make inroads in the region, U.S. officials are participating more across Latin America.
So far, Operation Enduring Promise 2018 has treated about 20,000 patients in Latin American countries.
Mattis and the outgoing SOUTHCOM commander praised the recent decision to send a U.S. Navy hospital ship to aid Venezuela.
Air Force Lt. Col. Rob Sweet retired this week as the deputy commander of the 476th Fighter Group at Moody Air Force Base.
It was the second long-range autonomous transit through the Navy's Ghost Fleet Overlord program.
Boeing Co. is behind schedule on two new Air Force One aircraft.
Capt. Durwood "Hawk" Jones of the 115th Fighter Wing out of Truax Field Air National Guard Base was instantly killed.
Maj. Gen. Robert Castellvi was in charge of the 1st Marine Division when an AAV sank off San Diego's coast last July.