Congress can’t modify any agreement but Congress can fund or not fund, make legal or make illegal the observing of terms of that agreement. If it is not a Treaty then it is nothing binding on Congress. It is just what 2 heads of state agreed to. Congress can’t change their agreement but Congress can determine what will be done or not done about the agreement.
Actually, there was no modification, as such, to the outlines of the treaty that have been proposed. It was a warning shot across the bow of the Current Regime that the Senate shall in no measure support ratification of the proposed agreement, and that any written agreement returned shall not be considered until it meets with the approval of three-fifths of the Senators (to close a filibuster), and is ratified by a two-thirds vote.
Mere majority is no longer enough.
Good explanation. Thanks.
Anyone two parties can agree to do something, there may be funding limitations and/or other constraints that effectively prevent the agreed upon terms from being a reality.