Senator John Cornyn from Texas said in his remarks at Washington-based think tank The Heritage Foundation that China has continuously under-reported its defence spending and has reinforced its territorial ambitions by making renewed claims in the East Sea or South China Sea and Arunachal Pradesh.
However, for the US the biggest concern remains China's ownership of a huge percentage of American debt amounting to $ 1.1 trillion of US securities.
"Just as our national debt is a huge challenge regardless of the Chinese connection, we know that China represents a challenge to our country above and beyond its investment in our debt.
"Many of China's neighbours remain concerned about its military build-up and its territorial ambitions," he said.
Cornyn, who also co-chairs the Senate India Caucus , said that China's official press agency reported in March that the country would increase its military budget this year by more than 12 per cent, an increase of 7 1/2 per cent.
However, he pointed out that the official Chinese estimates were "wrong".
"The Chinese repeatedly underestimate the extent of their defense spending. The Pentagon estimates the Chinese official budget of some $ 90 billion is far less than the $ 150 billion that they will actually spend. So it's off by $ 60 billion, the Pentagon estimates," he said.
Related to China’s moves in the East Sea, before Senator Cornyn, some American senators expressed their concerns. The US Senate on Monday approved a resolution condemning the repeated use of force by China in the East Sea and calling for a peaceful, multilateral resolution to maritime territorial disputes in Southeast Asia.