Senators, Russians and allied leaders who insist that the U.S. must not depart fromthe ABM Treaty understand full well thepracticaleffect of this arrangement.
Evidently, it took that much time and that much bureaucratic thrashing to wear down opposition from within the Obama administration to the only practicaleffect such a vision can have: disarming the United States.
One reason perhaps is that although the Russians seem to be keen on such a regime, the US has not elicited enough concessions in principle on law enforcement to make this worthwhile from their perspective (notwithstanding the probable lack of practicaleffect of such an agreement also).
That was certainly thepracticaleffect when it blocked prosecutors from bringing charges against Muslim Brotherhood fronts listed as unindicted co-conspirators in the Holy Land Foundation money-laundering case.
This injunction had thepracticaleffect of limiting Israeli efforts to press officials in Beirut to disassociate themselves fromthe terrorists in their midst.
This was thepracticaleffect of a seemingly minor bookkeeping adjustment one which changed the basis of American aid from grants to loans at roughly commercial interest rates.