K-21 armored vehicles will return to military use in April after defects that sank two of them in 2009 and last year were fixed, an official at the military acquisition agency said Thursday.

After it sank during a river-crossing training session in July, killing one solider, the domestically-built K-21, which was touted as a high-tech amphibious infantry fighting vehicle, was found to have a series of design faults.

“In order to address problems, we have conducted tests on it four times and fixed all the defects that the inspection team at the Ministry of National Defense pointed out,” the official at the Defense Acquisition Program Administration said, requesting anonymity.

“We will address complaints raised by field units this month and begin manufacturing component parts for it. In March, a final test on it will be conducted and the deployment will resume in April.”

The development of the 25-ton K-21, which began in December 1999, was completed in July 2007, at a cost of 91 billion won ($81.8 million). The armored vehicle was intended to be a major part of the nation’s forces in any future ground battles.

After several months of investigation to find the cause of the sinking last year, the military announced that the vehicle had defects in its design that made it difficult to keep its balance in the water without enough troops aboard it.

“We tested the vehicle for its amphibious operation both without people inside it and with people aboard it. We fixed the problems stemming from weak buoyancy in its front,” another DAPA official said, refusing to be named.

The military plans to deploy some 100 K-21 vehicles this year, including 50 vehicles whose deployment was suspended last year after the July sinking. The military is also considering legal procedures for those responsible for the defects in the vehicle.

By Song Sang-ho  (sshluck@heraldcorp.com)