U.S. Pacific Command Commander Adm. Harry Harris Jr., front, answers questions during a news conference Tuesday in front of PAC-3 launching station at Osan Air Base in Pyeongtaek, South Korea. (Lee Jin-Man/AP)

Two top U.S. commanders said Tuesday that diplomacy and economic actions are the first tools to be deployed against North Korea, with military force used only when the other measures don’t work.

As joint exercises between the American and South Korean militaries take place this week, some analysts expect that North Korea may launch another missile or take some other provocative action to register its disapproval.

On the second day of the Ulchi Freedom Guardian drills, which mainly involve computer simulations, North Korea’s state media issued another sharp warning to the United States. “The U.S. will be wholly held accountable for the catastrophic consequences to be entailed by such reckless aggressive war maneuvers,” it said.

But top military brass arriving in South Korea for the exercises tried to take the heat out of some of the recent rhetoric that has been flying back and forth between Pyongyang and Washington.

“The most important starting point is the diplomatic starting point,” Adm. Harry Harris, chief of the Hawaii-based Pacific Command, said at a news conference at Osan Air Force base, south of Seoul.

Secretary of State Rex Tillerson Aug. 22 welcomed what he called the "restraint" North Korea has shown recently and said it could mean a path to dialogue is opening. (Reuters)

With Patriot missile batteries lined up behind him, Harris said: “We hope and we work for a diplomatic solution to the challenge presented by [North Korean leader] Kim Jong Un. A strong diplomatic effort backed by a strong military effort is key. Critical combat power should be supporting diplomacy and not the other way around.”

Harris is in South Korea for the start of the annual exercises, along with Gen. John Hyten, head of U.S. Strategic Command, and Lt. Gen. Samuel Greaves, director of the Missile Defense Agency.

Together they have been underscoring the U.S. military’s readiness to act, but at the same time have been echoing the measured words of U.S. Defense Secretary Jim Mattis and Gen. Joseph F. Dunford Jr., chairman of the Joint Chiefs of Staff, who was in Seoul last week.

The tempered talk contrasts sharply with President Trump’s warning to North Korea that the U.S. military was “locked and loaded” to respond if provoked.

Still, the military exercises were “very important,” Gen. Vincent Brooks, commander of U.S. forces in Korea, said. “We have the responsibility of providing military options to our national leaders, and exercises are a way of making sure that this option is a ready option, it's a capable option,” Brooks said, adding that this helps deter North Korea from acting.

The Fact Checker explains what happened to the once not that distant goal of a nuclear deal with North Korea. (Meg Kelly/The Washington Post)

Still, the August exercises are smaller than usual this year, with 17,500 American troops participating, down from 25,000 last year. Mattis has said the decrease in troops was due to operational reasons, rather than to tamp down tensions on the Korean Peninsula. .

In addition to a recent slew of angry statements from Kim’s regime, North Korea put out a video with a calendar marking the days the exercises will take place and suggesting that another missile launch might be coming.

But Brooks noted there had been no missile launches this month, although North Korea launched its first and second intercontinental ballistic missiles last month.

“That means there may be some success in the diplomatic efforts,” Brooks said.

U.S. intelligence officials have concluded that North Korea has successfully produced a miniaturized nuclear warhead that can fit inside its missiles, crossing a key threshold on the path to becoming a full-fledged nuclear power.