The US has halted efforts to retrieve the remains of its troops killed during the Korean War amid a breakdown in communication with North Korea.
North Korea last year handed over the remains of more than 50 US servicemen killed in the 1950-1953 conflict.
It was a sign of improved relations between US President Donald Trump and North Korean leader Kim Jong-un.
But the Pentagon on Wednesday said the programme had been halted following a failed summit between the two leaders.
Some 36,000 American soldiers died during the Korean War and the US says more than 7,700 remain unaccounted for.
Around 5,300 of these soldiers were lost in North Korea.
The joint effort to return the bodies of US soldiers marked the partial fulfilment of an agreement reached between Mr Trump and Mr Kim during their historic first meeting in Singapore in 2018.
But communications halted following a second summit in Vietnam this year in which the leaders failed to make progress in talks over Pyongyang's nuclear programme.
Chuck Prichard, a spokesman for the Defense POW/MIA Accounting Agency (DPAA), said on Wednesday that North Korean officials had not communicated with the agency since the February summit.
"As a result, our efforts to communicate with the Korean People's Army regarding the possible resumption of joint recovery operations for 2019 has been suspended," he said in a statement.
"We have reached the point where we can no longer effectively plan, coordinate, and conduct field operations" with North Korea.
Tensions have risen since the Vietnam summit between Mr Kim and Mr Trump ended without agreement.
Amid a breakdown in communication between the countries, Pyongyang tested several short-range missiles on Saturday.
South Korea said the missiles were fired from the Hodo peninsula in the east of the country.
The missile launch, the first since Pyongyang tested an intercontinental ballistic missile in November 2017, came after the country tested what it described as a new "tactical guided weapon" last month.
Following the launch, Mr Trump tweeted that he believed Mr Kim “realizes the great economic potential of North Korea, & will do nothing to interfere or end it.”
"He also knows that I am with him and does not want to break his promise to me," he wrote.
South Korea announced on Tuesday that Mr Trump was supporting its plan to provide humanitarian food aid to North Korea amid reports that it had suffered its worst harvest in decades, leading to chronic food shortages.
In a 35-minute phone call, Mr Trump and South Korean President Moon Jae-in discussed ways to continue dialogue with North Korea in spite of the weapons test, the South Korean presidency said in a statement.
"President Trump assessed that South Korea's food provision to North Korea as a humanitarian effort will be a very timely and positive measure and he supported this," it said.