US Secretary of Defence James Mattis met his Chinese counterpart, General Wei Fenghe, for 1½ hours on Thursday on the sidelines of the Asean Defence Ministers' Meeting, after weeks of deepening tensions that included a nearcollision between two warships in the South China Sea. Yesterday, Mr Mattis assured Asean defence ministers at an informal meeting that the United States seeks a constructive relationship with China and wants to cooperate on the denuclearisation of North Korea. While he again expressed his concern over the ''militarisation of the features in the South China Sea'', Mr Mattis said he and Gen Wei agreed that they wanted a military relationship that would be a source of stability for the two powers.