The Navy has three carrier strike groups currently in the Pacific where North Korea’s nuclear saber rattling has the U.S. and its Asian allies keeping a close watch on the pariah state.

The last time the Navy operated three carriers together in the Pacific Fleet was back in 2007, and the current show of force comes just before an upcoming state visit to South Korea by President Donald Trump.

“Three carrier groups is certainly a robust force,” said Dean Cheng, a defense expert and senior research fellow at the Heritage Foundation, a Washington-based conservative think tank.

Defense experts say the carrier-based aircraft has the ability to perform a preemptive strike against North Korea and fleet escort ships could fire cruise missiles. The North’s new air-defense system, though, might be capable of intercepting the military aircraft and missiles.

“This gives us the ability to actually do something as opposed to other kinds of military-symbolic gestures,” said Denny Roy, an Asia Pacific security expert and senior fellow at the East-West Center, a think tank in Honolulu. In the past, he said, the U.S. has tended to use symbolic flights of aircraft along the border or sending a single ship near North Korea.

The carrier power in the Pacific comes as the Pentagon’s top general — Marine Corps Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff — is in South Korea to meet with leaders of South Korea’s military “to examine strategies, plans and means needed to deter any North Korean aggression,” according to the Department of Defense.

Asked by reporters traveling with him about the three carriers in Pacific waters — the USS Nimitz, the USS Reagan, the USS Theodore Roosevelt — Dunford said it was coincidental. Defense Secretary James Mattis, visiting the Demilitarized Zone on Friday, said “our goal is not war” but rather denuclearization of the Korean Peninsula, according to the Yonhap news agency.

Regardless, experts see a risk still of a catastrophic misunderstanding given the tensions. North Korean leader Kim Jong Un is also a wild card because he might pull the trigger first if he believes the U.S. is about to strike his regime.

“Miscalculation could come from how does North Korea interpret three carrier strike groups in the region,” said Anthony Ruggiero, a senior fellow at the Foundation for Defense of Democracies, a Washington think tank.

Even so, Ruggiero said he was encouraged by recent comment from Secretary of State Rex Tillerson that there are several avenues for diplomatic talks. “One of those channels could be used to de-escalate something that could escalate into a conflict,” he said.

Data from the Center for Strategic and International Studies on North Korean missile launches and provocations shows the months of November, December and early January “tend to be more quiet,” said Lisa Collins, fellow with the Korea Chair at CSIS, a Washington think tank. She explained that the country’s cold weather can create technical problems during missile launches.

Collins said that pattern of decreased provocations could create an opportunity for “more exchanges of dialogue or reaches out to North Korea through back channels.” (She added that she doesn’t have firsthand information on whether it’s happening now.)

Still, Reuters reported Wednesday a North Korean diplomat repeated the dynastic regime’s threat to conduct an atmospheric hydrogen bomb test over the Pacific.

“Are they serious about it — in my personal opinion yes,” said the Heritage Foundation’s Cheng. He said the last few underground nuclear tests by Pyongyang have been greeted by Washington and international officials with “open skepticism about whether or not it’s a hydrogen bomb.”

To prove he has the superbomb, the North Korean leader will “do an open air test and then there won’t be any questions,” Cheng said.