The United States would deploy 640,000 more troops to defend its South Korean ally if war broke out on the Korean peninsula, South Korea's defense ministry said on Wednesday.

The defense ministry's White Paper, which details military information related to the Korean peninsula annually, also said famine-struck North Korea has boosted its military capabilities in the past year, despite a debilitating economic crisis."If (war broke out) the United States would deploy (combined) armed forces to South Korea, mostly from bases in Japan and Hawaii under the United States Pacific Command," the White Paper said.

North and South Korea remain technically at war nearly half a century after their 1950-53 conflict ended in a now fraying truce, rather than a permanent peace accord.

The United States maintains 37,000 troops in South Korea, operates two air force bases on its own and four others jointly with South Korea.

The U.S. military has assigned sufficient troop numbers under the Pacific Command for any urgent mobilization, the defense ministry report said.

The White Paper said North Korea boosted its military personnel to 1.16 million, up 13,000 troops from a year ago. The North has also boosted its reserve units by an additional 900,000 troops to 7.45 million, the report said.

North Korea has added 14 more commando brigades to improve its surprise attack capabilities against South Korea, it said.

North Korea also increased its number of navy ships to 990, including 40 submarines, from 810 last year. North Korea's total number of field artillery guns rose to 12,000 from 11,200 a year ago, it said.

By comparison, South Korea currently has a total 4,850 field artillery and 200 naval ships, six submarines and a total 730 planes and 570 helicopters.

South Korea's total defense budget for this year was reduced by 1.35 trillion won ($971 million) to 13.8 trillion won, or a 15 percent drop from its earlier budgetary target of 14.63 trillion won due to the current economic crisis, it said.