"Not out of amity, but rather because of an absence of tenable alternatives, both countries will need to find a new and enduring framework for managing the relationship," the Brookings Institution said in a policy analysis titled "Rising to the challenge: Navigating competition, avoiding crisis, and advancing US interests in relations with China", which was released over the weekend.

出处：http://global.chinadaily.com.cn/a/202111/08/WS618896bca310cdd39bc73fd7.html

请问这里的alternatives指代什么？