China is extending its military advantage over Taiwan and increasingly looking beyond, building-up a force with the power to strike in Asia as far as the US territory of Guam. The US Department in an annual report to Congress said that China was ramping-up investment in an array of areas including nuclear weapons, long-range missiles, submarines, aircraft carriers and cyber warfare. The report further said the balance of cross-Strait military forces continues to shift in the mainland's favour. The Pentagon said China's military build-up on the Taiwan Strait has continued unabated despite improving political and commercial relations since the island elected Beijing-friendly President Ma Ying-jeou in 2008.