China is deploying missiles in the disputed South China Sea to intimidate and coerce its neighbours, US Defence Secretary James Mattis has said, BBC reports.
Speaking in Singapore, General Mattis said Beijing's actions called into question its broader goals.
He also said the issue of US troops in South Korea was "not on the table" at this month's summit between President Trump and North Korea's Kim Jong-un.
The US wanted complete denuclearisation of the Korean peninsula, he added.
South Korean Defence Minister Song Young-moo also told the Shangri-La Dialogue security summit that US forces in South Korea was a "separate issue from North Korea's nuclear issue".
There are currently about 28,500 US troops based in South Korea.