1.   In recent years, those ties have become frayed.

2.   His detention has strained Sino-U.S. relations at a time when ties were already frayed by disputes over Taiwan, trade and arms sales.

3.   Previously, there was a rumour that a prolonged air-traffic rights dispute could fray bilateral ties between both countries.

4.   The spy flap comes at a time when U.S.-Japanese ties are already frayed over other issues.

5.   U.S.-Russia ties have been frayed recently, but both Powell and Russian Foreign Minister Igor Ivanov indicated in a joint news conference they were seeking more cooperation.