ratchet up 徐々に上がる

Pyongyang so far has rejected US overtures, accusing Washington and Seoul of talking diplomacy while ratcheting up tensions with their own military activities.

retaliatory

仕返し　respond

Missiles fired from submarines are harder to detect in advance and would provide North Korea with a secondary, retaliatory attack capability.

provocative挑発的

annoying

US urges N Korea to end ‘provocative’ tests, return to talks