The Congress on Wednesday expressed concern over the reported Chinese buildup close to the Doklam plateau, and said it poses a grave security threat and Prime Minister Narendra Modi should break his "silence" on the issue.

In a statement, Congress general secretary Jairam Ramesh alleged that the Modi government has failed to restore the status quo ante on the Line of Actual Control for three years and urged the Union home minister to restore it instead of making "misleading claims".