Two recently released government reports show that the worldwide nuclear threat is getting more complex and more dangerous.

The Defense Science Board (DSB) report shows how hard it can be to develop plans for even monitoring the nuclear landscape. For starters, the nuclear landscape is changing all the time: The number of actors involved worldwide in making and sharing nuclear technologies and information is large and growing, as is the geographic space in which they operate.

And because actors don’t want the U.S. to know what they are doing, it is difficult to know if the mechanisms we have in place through treaties and agreements are there for monitoring or intelligence-collecting purposes. The problem is made even harder when one considers that some materials and platforms can be used for non-military purposes.

The Director of National Intelligence (DNI) also released a report that concludes that if Iran did achieve a nuclear weapon and decided to use it, it would do so by launching it on a missile. Evidence for this includes the massive size of Tehran’s missile force, which is unparalleled in the Middle East, its dogged determination to make the launch vehicles work, and the regime’s desire to deter the United States, specifically. It can’t deter the much more sophisticated U.S. military with conventional means alone, but it could if it had a nuclear missile able to reach American soil.

The DNI’s report also affirms that Iran continues to receive help from another bad actor—North Korea, which sends ballistic missiles and the pieces and parts that go with them to not only Iran but to Syria as well.

There are two takeaways from these two reports: First, American security in the 21st century cannot be guaranteed by arms control methods. As the DSB report illustrates, even figuring out who has what and what it actually does is extremely difficult. And even if we strike a deal with one country, there remain other countries unrestrained by those agreements. Moreover, some agreements come at a high cost to the U.S. and do not ultimately lower the security risk.

For instance, the nuclear deal Iran just struck with the West turns a blind eye to its missile program, and the implementation of an agreement to remove chemical weapons from Assad’s Syria has languished. And as The New York Times reported a few days ago, while the Obama Administration works toward striking another arms control deal with the Russians, Moscow has been cheating on current treaty agreements.

Second, the U.S. should not limit its own nuclear deterrent capabilities or missile defense systems either by failing to invest in their modernization or by purposefully limiting their capabilities out of a fear of upsetting other nations such as Russia or China. Today’s security environment is far too complex, and the stakes are too high. The U.S. should maintain a nuclear arsenal that is second to none and a defensive capability that stays ahead of the increasing missile threat.