By Michelle Nichols UNITED NATIONS (Reuters) -The United States on Wednesday questioned whether China and Russia had elevated their “no limits” strategic partnership above global security by vetoing more U.N. sanctions on North Korea over its renewed ballistic missile launches. “We hope these vetoes are not a reflection of that partnership,” senior U.S. diplomat Jeffrey DeLaurentis told a meeting of the 193-member U.N. General Assembly in response to the vetoes in the Security Council two weeks ago. “Their explanations for exercising the veto were insufficient, not credible and not convincing….