Nrog rau kev txhim kho kev lag luam, kev tiv thaiv hauv tebchaws thiab kev tshawb fawb thiab thev naus laus zis, tshwj xeeb tshaj yog kev txhim kho aviation, tsheb tsim, nuclear, foob pob hluav taws, missile, chaw siv tshuab, thiab tshuab tsim kev lag luam, qhov yuav tsum tau ua kom muaj kev loj hlob ntawm kev nce siab ...
Nyeem ntxiv