The US and South Korea will postpone their annual joint drills due to concern about a viral outbreak that has infected soldiers in both countries’ armed forces.

Twenty South Korean soldiers and one American service member in South Korea have tested positive for the new coronavirus, which has infected about 1,600 people in the Asian country, the second largest outbreak outside mainland China.

In a joint news conference, South Korean and US military officers said their joint drills planned for the first half of this year will be put off until further notice.

South Korean military chief Park Han-ki proposed the delay out of concerns for troop safety and Robert Abrams, the commander of the US military in South Korea, accepted Mr Park’s proposal based on the severity of the virus outbreak.

A South Korean soldier wearing a protective suit sprays disinfectant to prevent the spread of Covid-19 on a street in Daegu
A South Korean soldier wearing a protective suit sprays disinfectant to prevent the spread of Covid-19 on a street in Daegu (Kim Hyun-tai/AP)

Lee Peters, a US military spokesman, said the postponement decision “was not taken lightly” and that two countries’ alliance remains “ironclad and unbreakable”.

In recent days, South Korea suspended some unilateral field training, placed 9,570 troops under quarantine and banned most of its enlisted soldiers from leaving their bases.

The US military closed some amenities at several bases and was urging its personnel to avoid handshakes and large gatherings if possible.

Experts say the postponement of the drills was inevitable because the potential spread of the virus into military barracks could significantly weaken military readiness.

The allies have previously suspended or scaled back their regular military exercises, but that was part of diplomatic efforts to disarm North Korea, which views the training as a rehearsal for an invasion.