The DEW Line and the NWS were put into place at a time of very different strategic context. Both of them were looking for Russian bombers, simply put. The DEW Line was quickly made obsolete by the arrival of ICBMs, but the NWS was brought in as an upgrade with the advent of Russian cruise missiles. The hard security threat we're facing today comes from new Russian weapons with much longer ranges. If this is of particular interest, I would direct committee members to a paper written by two NORAD officers, Fesler and O'Shaughnessy, called “Hardening the Shield”. They do a very good job of outlining the strategic considerations and threat.
Today that danger is still Russian hard power. It is still Russian bombers and weapons that could theoretically be launched from the Arctic as first-strike weapons. However, it's a very different context in the sense that we need a much more holistic look at surveillance, because it is not just Russian bombers we're looking for, as was the case in the 1950s, but now civilian craft, maritime militia, hybrid threats, illegal fishing fleets, trespassing and pollution threats. All manner of different aerospace and maritime threats are emerging.
What is required is a much more complex, holistic system of systems that allows Canada and the United States to gain a much more complete situational awareness.