Before the Russian invasion of Ukraine, the Biden administration insisted in arms control talks with Russia that a follow-on agreement to the New Strategic Arms Reduction Treaty (New START) should cover all nuclear weapons and that such an agreement should focus on the nuclear warheads themselves. This would represent a significant change from previous agreements, which focused on delivery vehicles, such as missiles. The United States has been particularly interested in potential limits on nonstrategic nuclear warheads (NSNW). Such weapons have never been subject to an arms control agreement. Because Russia possesses an advantage in the number of such weapons, the US Senate has insisted that negotiators include them in a future agreement, making their inclusion necessary if such an accord is to win Senate approval and ultimately be ratified by Washington. In the wake of Russian nuclear threats in the Ukraine conflict, such demands can only be expected to grow if and when US and Russian negotiators return to the negotiating table.