Last week, Congress passed the fiscal year 2018 National Defense Authorization Act (NDAA), sending it to the president’s desk. This bill advances many commendable nuclear weapon and missile defense policies.

The bill affirms Congress’s commitment to ensuring strong, extended measures of deterrence, and it addresses Russian arms control violations—including their potential violations of the New Strategic Arms Reduction Treaty (New START).

In the bill, Congress prompts the administration to explore potential retaliatory measures like economic sanctions, diplomacy, additional missile defense deployments, increasing U.S. nuclear deployments above New START limits, and other legal countermeasures.

If recent reports in the Russian press that Russia intends to deploy 400 intercontinental-range ballistic missiles (ICBMs) are correct, Russia could exceed the number of operationally deployed warheads that are permitted under New START, which demands an official accounting as of February 2018.

Moscow has exceeded the treaty warhead limits for years.

With regard to another significant Russian violation—that of the Intermediate-Range Nuclear Forces (INF) Treaty by deploying a nuclear ballistic missile of a prohibited range—Congress takes the reasonable position that the U.S. can suspend the operation of the treaty until Russia comes back into compliance with its terms.

Additionally, Congress provides funds for research, development, test, and evaluation of capabilities that would help the United States counter the Russian threat, and establishes a program of record for the development of a conventional INF-range, road-mobile, ground-launched cruise missile.

The bill also calls for sanctioning entities affiliated with the Russian INF program.

These are steps in the right direction. The United States can no longer afford to ignore Russian violations.

The bill would unwisely prohibit funds for mobile variants of a ground-based strategic deterrent missile through 2019. The United States must be able to evaluate all options without pre-determined constraints. A mobile ground-based strategic deterrent missile could be the most survivable mode of deployment for this type of a system.

On a more positive note, the NDAA prohibits reducing alert levels of the current ICBM force, and reducing the number of ICBMs below 400.

The NDAA signals solid bipartisan support for ensuring the U.S. deterrent remains safe, secure, reliable, and credible for U.S. allies. The bill lays the groundwork for continuing deterrence dialogues with U.S. partners and supporting nuclear cooperation with NATO.

The NDAA also emphasizes the need to modernize U.S. nuclear weapons infrastructure. It places additional emphasis on the exercise of nuclear warhead design activities.

The United States has not significantly engaged in such activities for years, despite a rapidly changing national security environment, even as hopes for a benign and peaceful future with nuclear-armed states have soured.

Missile defense policies advanced in the NDAA recognize a growing ballistic missile threat to the U.S. homeland, Hawaii, and our allies, particularly from North Korea. The bill signals congressional support for initiatives that the administration ought to pursue in its Ballistic Missile Defense Review, including calling for a designation of a third ballistic missile defense site in the continental United States and calling for the deployment of additional ground-based midcourse defense interceptors.

The NDAA also addresses a major gap in U.S. missile defense capabilities: a lack of a serious effort to boost phase ballistic missile defense. Ballistic missiles in the boost phase of their flight are the slowest. They have not deployed countermeasures, which makes them uniquely vulnerable to intercepts.

Finally, the NDAA also indicates congressional support for a space-based interceptor and sensor layers, a complimentary domain for layered comprehensive missile defense capabilities. Such an architecture could augment existing data from relatively more vulnerable ground and sea-based assets.

Congress and the administration ought to build on these sound proposals in the years ahead and fully fund programs that keep America and its allies safe.