Mattis says no decision yet on suspending more South Korea exercises

Suspending August exercise was a "good faith effort," Mattis said.

"As you know, we took the step to suspend several of the largest exercises as a good-faith measure coming out of the Singapore summit," said Mattis at a Pentagon news conference Tuesday. "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 we will certainly do to reinforce his effort," said Mattis. "But at this time, there is no discussion about further suspensions."

Mattis later explained that while the joint Ulchi Freedom Guardian exercise with South Korea had been suspended from taking this place this month, no decisions had been made about the Foal Eagle exercise slated for early next year.

"We have not made decisions on that at this time and we'll do that in consultation with state," said Mattis, suggesting that the State Department would have a say depending on how talks with North Korea are progressing.

Mattis' comments Tuesday echoed the Pentagon's statement in June that announced the suspension of the Ulchi Freedom Guardian exercise, and that no decisions had been made about future exercises.

While the Pentagon suspended the large scale Ulchi Freedom Guardian exercise, it has continued to carry out joint exercises with South Korea up to the battalion level. But those exercises have not been publicized.

"There are ongoing exercises all the time on the peninsula," Mattis said. "The reason you've not heard much about them is North Korea could not in any way misinterpret those as somehow breaking faith with the negotiation."

But the optimism generated by President Donald Trump's summit meeting in June with North Korea's Kim Jong Un has ebbed as North Korea has yet to make a firm commitment to denuclearize.

Last week Trump cited a lack of progress in calling off Secretary of State Mike Pompeo's scheduled trip to North Korea for another round of talks aimed at denuclearizing North Korea.

Mattis said he had no "crystal ball" as to whether North Korea might see those new exercises as being "provocative," the term commonly used by North Korea to characterize the exercises. Trump also used the term after his meeting with Kim when he announced the U.S. was suspending what he called "war games".

"Let's see how the negotiations go," said Mattis. "Even answering a question in that manner could influence the negotiations."

"We will work very closely, as I said, with the secretary of state, and what he needs done we will certainly do to reinforce his effort," Mattis said. "But at this time, there is no discussion about further suspensions."

The US remains "ready to engage" North Korea "when it is clear that Chairman Kim stands ready to deliver on" his commitment in Singapore to denuclearize, State Department spokesperson Heather Nauert said, reading a statement from Secretary of State Mike Pompeo at Tuesday's State Department briefing.

ABC News' Conor Finnegan contributed to this report