Under Secretary of State Thomas G. DiNanno

I'm honored to serve as Under Secretary for Arms Control & Int'l Security & grateful to @POTUS & @SecRubio for their confidence. Alongside the talented professionals of the bureaus and offices within my remit, I will faithfully execute @POTUS 's mission of achieving peace through strength. Stay tuned for updates on how we’re tackling the tough security challenges of the day.

Thrilled to announce the completion of the U.S.-El Salvador 123 Agreement negotiations with @Daalvarezc today. Along with @MilenaMayorga, committed to work together on necessary steps prior to signing and bringing agreement into force. This milestone strengthens 🇺🇸🇸🇻 bilateral partnership, advances energy security, and supports economic cooperation! @USEmbassySV #USElSalvador #EnergyDiplomacy

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CAPTURED. Sebastian Marset’s reign of terror and chaos is over. Thanks to President @Rodrigo_PazP's leadership and rapidly strengthening U.S.-Bolivia law enforcement cooperation, notorious drug trafficker Marset will face justice. The Shield of the Americas is making our region safer and stronger.

At #CND69 in Vienna, we're calling on countries to drive down illicit drug supplies at the source, as the Trump Administration is doing, and to ruthlessly scrutinize funded programs to ensure real impact.

Useful conversation w/Thomas DiNanno, @UnderSecT for Arms Control & Int’l Security on deepening 🇦🇲-🇺🇸 strategic partnership in various directions. Emphasized readiness to sign the 123 Agreement on Nuclear Energy. Touched upon regional infrastructure projects.

On the margins of the @iaeaorg Nuclear Energy Summit #NES2026, I also held fruitful discussions with bilateral nuclear energy partners to discuss the mutual benefits of the Trump Administration's four executive orders jump-starting the 🇺🇸 nuclear energy renaissance.

Yesterday, I attended the @iaeaorg Nuclear Energy Summit to deliver remarks on behalf of the USA. “We must strengthen the global nuclear energy supply chain so that no nation is forced to rely on unsafe or coercive alternatives.” Thanks to U.S. Department of @ENERGY and @WhiteHouse Chief Technology Office for support. #NES2026

In my meeting with @rafaelmgrossi, we discussed how the United States and @iaeaorg collaborate on some of the world’s toughest challenges.

Met Monday with my French counterpart, Claire Raulin, Director for Strategic Affairs, Security, and Disarmament at the French Ministry for Europe and Foreign Affairs for the 🇺🇸 🇫🇷 Deterrence, Strategic Stability and Non-Proliferation Dialogue in Paris. We discussed a range of nuclear related issues as well as the current strategic challenges facing our two countries. state.gov/releases/offic…

The Sudanese Muslim Brotherhood, trained and supported by Iran’s Islamic Revolutionary Guard Corps, has been designated by @StateDept as a Foreign Terrorist Organization and Specially Designated Global Terrorist for mass executions of civilians. We will continue to use all available tools to deprive the Iranian regime and Muslim Brotherhood chapters of the resources they need to engage in or support terrorism.

Productive meeting with @GermanAmbUSA Hanefeld this morning. 🇺🇸 and 🇩🇪 reiterated our unwavering commitment to extended nuclear deterrence in @NATO and to the trans-Atlantic cooperation essential to U.S. strategic security. Our pursuit of new, improved, and modernized nuclear arms control strategies after New START will benefit U.S. and European security.

Excellent discussion today with @FrenchAmbUS Laurent Bili. France is a crucial @NATO ally on a wide range of shared security interests from nuclear nonproliferation to high-tech to counterterrorism. 🇺🇸🤝🇫🇷

I had a good discussion today with Vice Minister for Diplomatic Strategy and Intelligence Jeong Yeon-doo. The USA-ROK alliance remains the linchpin of peace, security, and prosperity for Northeast Asia, supported by our ironclad extended nuclear deterrence.🇺🇸🤝🇰🇷

Assistant Secretary Christopher T. Yeaw delivered a U.S. national statement at the Conference on Disarmament on the next era of multilateral nuclear arms control. Read the full statement here: geneva.usmission.gov/2026/02/23/sta…

The United States commends Mexico for the successful operation that resulted in the elimination of Nemesio ‘El Mencho’ Oseguera Cervantes, the leader of the designated foreign terrorist organization Jalisco New Generation Cartel (CJNG), thereby ending his reign of terror. We honor the bravery and sacrifice of Mexico’s military and law enforcement personnel in this fight and commend their decisive execution of this operation. apnews.com/article/mexico…

This week, I addressed the U.S.-Japan Extended Deterrence Dialogue to reinforce our unwavering commitment to the U.S.-Japan Alliance and discuss the growing nuclear threats we face.🇺🇸🇯🇵 state.gov/releases/offic…

Denials by China only make it worse. We look forward to dialogue that will advance President Trump’s vision for a world with fewer nuclear weapons. For now, we cannot accept nuclear tests by other states that place us at an intolerable disadvantage. (2/2)

Today, Dr. Chris Yeaw, Assistant Secretary for Arms Control and Nonproliferation @StateACN, provided additional information in a talk at @HudsonInstitute about Chinese nuclear testing activities that violate Beijing’s own commitments to the international community. On June 22, 2020, at 0918 GMT, the monitoring station at Makanchi, Kazakhstan (PS23) detected a 2.75 magnitude seismic event in the vicinity of Lop Nur, China. (1/2)