The United States was not forewarned of South Korea's recent decision to terminate a military intelligence-sharing pact with Japan that helps the U.S. allies counter missile threats from North Korea, a senior U.S. defense official said Wednesday.

Noting that there have been "consultations" over the issue, Randall Schriver, assistant secretary of defense for Indo-Pacific security affairs, said at a Washington think tank, "In terms of the actual decision to not renew (the pact), we were not forewarned."

His remarks at the Center for Strategic and International Studies came as the U.S. government is showing strong concern that a diplomatic row between Japan and South Korea over wartime history and trade is also affecting their bilateral defense cooperation.

"Historical disputes, animosities and political disagreements should be kept separate from shared vital military and security cooperation," Schriver said, urging South Korea to "recommit" to the General Security of Military Information Agreement, known as GSOMIA, and renew it.

U.S. Defense Secretary Mark Esper said at a press conference later in the day that he is "very disappointed" the two countries are engaged in the spat.

"I'm hopeful that they'll get beyond this...we have common threats facing us -- North Korea and China and bigger threats," he said.

Also at the press conference, Gen. Joseph Dunford, the highest-ranking military officer of the United States, said that he has not yet seen any impact in military operations but that he shares the "secretary's disappointment."

Signed in November 2016, GSOMIA was facing a deadline last Saturday for either side to give written notification of their intent to pull out. South Korea said Thursday it had decided to scrap the agreement, setting the stage for its expiration on Nov. 22.

Schriver said GSOMIA has allowed the two countries to share sensitive intelligence information directly and in a timely way, which otherwise would have had the United States in the middle passing information back and forth between the two parties.

"We emphasize the only winners when Japan and Korea feud are our competitors," the official warned.

He also called on both South Korea and Japan to engage in "meaningful" dialogue to address their differences, which he said means that the two should come to the table with "a mindset of problem-solving, not with a mindset of airing grievances further."

Tokyo and Seoul have seen their bilateral ties worsen over South Korean court rulings last year ordering compensation for what they recognized as victims of forced labor during Japan's colonial rule of the Korean Peninsula from 1910 to 1945.

An alleged radar lock-on incident involving a Japanese patrol plane and a South Korean warship last year also fueled tension, and spilled over to trade issues, with Japan implementing in July tighter controls on exports of some materials needed by South Korean manufacturers of semiconductors and display panels.

On Wednesday, Japan removed South Korea from a list of countries that enjoy minimum trade restrictions on goods such as electronic components that can be diverted for military use. South Korea said in mid-August that it will take measures apparently in retaliation.