The addition of countries to NATO is seen as an asset by the foreign policy establishment in the US, but the speaker argues that it is actually a liability. They believe that joining NATO requires the US to provide defense for these countries, even if it means sending American troops to war. The speaker questions whether the security of the US is benefited by having countries like Sweden or Finland in NATO, as it is uncertain how these countries would defend the US. The speaker considers the expansion of NATO as a commitment that obligates Americans to defend other nations, which they perceive as a liability for the US. However, they acknowledge that joining NATO benefits the military industrial complex, as countries are required to spend 2% of their GDP on defense and can only use that money on NATO-approved contractors. The concept of interoperability is essential for countries to join NATO, meaning that their military should use weapons, tactics, and strategies approved by NATO.