The commander of U.S. forces in the Pacific told Congress he lacks the spy aircraft needed to verify any "denuclearization" agreement that might come out of the proposed summit between President Donald Trump and North Korean leader Kim Jong-un.

"I don't have enough because there isn't enough to go around," Adm. Harry Harris, commander of U.S. Pacific Command, said of the available intelligence, surveillance and reconnaissance (ISR) assets at a hearing of the Senate Armed Services Committee last Thursday.

In response to questions from Sen. Deb Fischer, R-Nebraska, Harris said Navy P-3 Orion surveillance aircraft, Air Force RC-135 Rivet Joint signals intelligence and WC-135 Constant Phoenix "sniffer" aircraft are vital to his mission monitoring North Korea's nuclear and ballistic missile programs.

All three aircraft are "critical to intelligence collection," he said, adding the WC-135 is taking on added importance following the stunning announcement that Trump had agreed to meet with Kim.

"I don't know where we're going to end up with the talks," Harris said, "[but] I do see demand increasing, clearly" for the use of the WC-135 and its top secret equipment that can collect atmospheric samples and determine whether nuclear testing has taken place.

The WC-135 "helps me understand the nature of North Korea's nuclear testing," he said.

The problem with ISR assets, Harris said, is that other combatant commands want them and they must be allocated by the Pentagon's Joint Staff.

"The WC-135, I have to ask for it and, when I ask for it, I get it," he said.

Harris had a suggestion for Trump that is a wrinkle on President Ronald Reagan's "trust but verify" axiom for arms reductions negotiations. In the case of talks with North Korea, "I think it's distrust but verify," he said.

"We have to enter this eyes wide open," Harris said, but "the fact that we're talking at all has a positive framework about it. We haven't lost anything by talking … the opportunity to engage has value itself regardless of the outcome."

South Korean President Moon Jae-in, who set the stage for the potential Trump-Kim summit by inviting North Korea to the Winter Olympics and then getting an offer from Kim to meet, pushed ahead over the weekend with preparations for the negotiations.

Moon's chief of staff, Im Jong-seok, said a high-level negotiating team would meet with North Korean counterparts later this month to lay the groundwork and set the agenda for Moon's anticipated meeting in April with Kim at the Panmunjom peace village in the Demilitarized Zone, South Korea's Yonhap news agency reported.

"This inter-Korean summit should be a turning point for fundamentally addressing the issue of peace on the Korean peninsula," Im said.

Yonhap quoted Moon as saying, "Our firm stance is that we can't make concessions [on denuclearization] under any circumstances and conditions" in the negotiations.

Trump caused a flap on his own agenda for the talks last week when his comments at a private fundraiser leaked. He appeared to suggest that he might pull U.S. forces out of South Korea unless the U.S. received more favorable terms on trade agreements.

"We have a very big trade deficit with them, and we protect them," he said, The Washington Post reported. "We lose money on trade, and we lose money on the military. We have right now 32,000 soldiers on the border between North and South Korea. Let's see what happens."

Trump glossed over the trade issue in a phone call to Moon on Friday in which he renewed his commitment to go ahead with the summit, probably at the end of May, although a time and place have yet to be set.

A White House readout of the phone call said Trump "reiterated his intention to meet with North Korean leader Kim Jong-un by the end of May. The two leaders expressed cautious optimism over recent developments and emphasized that a brighter future is available for North Korea, if it chooses the correct path."

In his appearance before the Senate Armed Services Committee, Harris was characteristically blunt on issues in the region.

Harris noted that his testimony would be his last before the committee. He will soon retire after 39 years of service and has been nominated by Trump to be the next ambassador to Australia.

On the North Korea talks, Harris said, "As we go into this, I think we can't be overly optimistic on outcomes. We'll just have to see where it goes if and when we have the summit. North Korea remains our most urgent security threat in the region."

"This past year has seen rapid and comprehensive improvement in North Korea's ballistic missile and nuclear capabilities despite broad international condemnation and the imposition of additional United Nations security resolutions," he said.

"It is indisputable that KJU [Kim Jong-un] is rapidly closing the gap between rhetoric and capability,” Harris added. “The Republic of Korea and Japan have been living under the shadow of North Korea's threats for years; now, that shadow looms over the American homeland.”

He scoffed at the notion that the Trump administration had been considering a so-called "bloody nose" strategy that would involve limited strikes on North Korea to rein in Kim's nuclear ambitions.

"We have no bloody nose strategy. I don't know what that is. The press have run with it," Harris said.

"I'm charged with developing, for the national command authority, a range of options through the spectrum of violence, and I'm ready to execute whatever the president and the national command authority directs me to do, but a 'bloody nose' strategy is not contemplated," he said.

The strategy that does exist, Harris said, is for full-spectrum warfare that would obliterate the North Korean threat.

"We have to be ready to do the whole thing, and we are ready to do the whole thing if ordered by the president," he said.

By way of farewell, Harris said that during his time at PaCom, "I have had the tremendous honor of leading the soldiers, sailors, Marines, airmen, Coast Guardsmen, and Department of Defense civilians standing watch for the largest and most diverse geographic command.

"These men and women, as well as their families, fill me with pride with their hard work and devotion to duty. I'm humbled to serve alongside them," he said.

-- Richard Sisk can be reached at Richard.Sisk@Military.com.