INS 在blockIV 就被取消了，concern .... from long distance

The previous Tomahawk Anti-Ship Missile, retired over a decade earlier, was equipped with inertial guidance and the seeker of the Harpoon missile and there was concern with its ability to clearly discriminate between targets from a long distance, since at the time Navy sensors did not have as much range as the missile itself, which would be more reliable with the new seeker's passive detection and millimeter-wave active radar homing.[29][30] Raytheon estimates adding the new seeker would cost $250,000 per missile.[31] Other upgrades include a sea-skimming flight path.[32][33] The first Block IV TLAMs modified with a maritime attack capability will enter service in 2021.[34]