"We have no plans at this time to suspend any more exercises. We will work very closely, as I said, with the secretary of State and what he needs done," he added, noting that forces on the Korean Peninsula have continued with small-scale training exercises.
The secretary's comments came on the heels of a canceled U.S. delegation trip headed by Secretary of State Mike Pompeo. Trump scrapped Pompeo's bilateral meeting because "sufficient progress" had not been made in regard to denuclearizing the Korean Peninsula.
Read more: Trump cancels Pompeo trip to North Korea, cites lack of progress on denuclearization
After meeting with reclusive North Korean leader Kim Jong Un in Singapore, Trump canceled the bilateral training exercise between the U.S. and ally South Korea, citing their "tremendously expensive" costs.
"We save a fortune by not doing war games, as long as we are negotiating in good faith — which both sides are!" Trump tweeted after his summit with Kim in June.
"I think it's inappropriate to be having war games. No. 1, we save money. A lot. And No. 2, it really is something that I think they [North Korea] very much appreciated," Trump said, adding that flying U.S. Air Force bombers in regional training missions was another drain on resources.
Trump's move falls out of step with the Pentagon, which has maintained that the joint exercises are routine, purely defensive and vital to maintaining readiness on the Korean Peninsula. Unlike Trump, Mattis avoided calling the exercises "war games" or "provocative."
There are currently 28,500 U.S. troops stationed in South Korea, a legacy of the Korean War, which halted in 1953 in an armistice that left the two Koreas technically still at war.