Mr.Bader is director of the John L.Thornton China Center at the Brookings Institution.Mr.Paal is vice president for studies at the Carnegie Endowment for International Peace.

• 正因为如此，美国必须审慎，一旦有所宣示，必须以实际行动表达明确的立场，促使潜在的侵略者不得不自制。