Christopher Landau is an American diplomat and lawyer who has served as the 23rd U.S. Deputy Secretary of State since March 25, 2025. He was previously the U.S. Ambassador to Mexico (2019–2021) and spent decades in private legal practice.
The U.S. Deputy Secretary of State is the second‑ranking official in the State Department. The Deputy Secretary is the Secretary of State’s principal deputy and adviser, can act as Secretary when the Secretary is absent, and helps oversee and direct all parts of the department and the conduct of U.S. foreign policy.
Greg Moriarty is an Australian career public servant and diplomat who has been Secretary of the Department of Defence (the top civilian official in Defence) since 4 September 2017. He previously served as Australia’s ambassador to Iran and Indonesia, Commonwealth Counter‑Terrorism Coordinator, and Chief of Staff to Prime Minister Malcolm Turnbull.
The Australian Secretary of the Department of Defence is the executive head of the Defence organization. The Secretary’s responsibilities include providing defence policy advice to the government, overseeing the department’s budget and resources, leading the civilian workforce, and, together with the Chief of the Defence Force, managing the overall direction and administration of Australia’s defence organisation.
The December 8, 2025 Australia‑U.S. Ministerial Consultations (AUSMIN 2025) in Washington agreed on a wide package of steps to deepen the alliance and shape the Indo‑Pacific security and economic environment. Key points included:
• Indo‑Pacific and regional security: new joint efforts to promote a “free and open Indo‑Pacific,” build resilience against economic coercion, expand coordination with partners like Japan and the Philippines, and cooperate on air and missile defense and maritime activities (including in the South China Sea). • Force posture and defense cooperation: accelerating U.S. force rotations and infrastructure in northern Australia (air bases and Marine Rotational Force–Darwin), establishing a Submarine Rotational Force‑West at HMAS Stirling, and deepening defense‑industrial cooperation, including co‑production and sustainment of advanced missiles under the Guided Weapons and Explosive Ordnance (GWEO) Enterprise and streamlining defense trade rules. • AUKUS and submarines: confirming work to build a trilateral submarine industrial base and additional Australian funding (totaling about US$2 billion so far) to expand U.S. submarine‑production capacity. • Economic and technology cooperation: implementing a Critical Minerals Framework and joint financing for projects that secure supply chains for key minerals (for example, support to Alcoa and Tronox projects), and coordination on strategic infrastructure and digital connectivity in Southeast Asia and the Pacific (such as undersea cables and port upgrades in Papua New Guinea). • People‑to‑people and border measures: extending U.S. Global Entry eligibility to all Australian citizens from December 15, 2025, and exploring a customs‑cooperation agreement.
These decisions provide the strategic backdrop for Landau and Moriarty’s later meeting, which “built on” AUSMIN 2025 and focused specifically on defense cooperation and regional security in the Indo‑Pacific.
Australia’s new defence treaty with Papua New Guinea is the Papua New Guinea–Australia Mutual Defence Treaty (often called the “Pukpuk Treaty”), signed on 6 October 2025.
What it covers (in simple terms): • Mutual defence pledge: both governments state that an armed attack on either country would endanger the peace and security of both, and they commit to act together to meet the common danger (a formal mutual‑defence obligation). • Alliance status and access: it elevates the relationship to an “Alliance” (Australia’s first new alliance in more than 70 years and PNG’s first with any country). It allows Australia access to PNG military facilities and PNG troops, and greatly expands joint exercises and training. • Expanded defence cooperation: the treaty provides for modernising and growing the defence relationship, including options for PNG citizens to serve in the Australian Defence Force and increased collaboration in areas like cyber and electromagnetic warfare.
Why it matters: • It locks in Australia as PNG’s primary security partner and gives PNG a formal security guarantee, which supporters argue will help deter external coercion or aggression. • It is a major piece of the wider contest over security influence in the Pacific; analysts note it is partly aimed at limiting opportunities for China or other outside powers to gain similar military access in PNG. • By integrating PNG forces and infrastructure more closely with Australia’s, it could significantly reshape Pacific security arrangements and Australia’s ability to project and sustain forces in the region.
Australia’s “expanded security ties” with Indonesia refer to a series of recent agreements that deepen military and security cooperation between the two neighbours:
• 2024 Defence Cooperation Agreement: a treaty‑level DCA signed in August 2024 allows more complex joint activities and exercises and greater interoperability between the Australian Defence Force and the Indonesian National Armed Forces. It covers areas such as maritime security, counter‑terrorism, humanitarian assistance and disaster relief, logistics support, training and education, and defence industry cooperation, and lets each side operate from the other’s territory for agreed activities. • Forthcoming 2025–26 security treaty: in November 2025 the two governments agreed in principle on a new bilateral security treaty, to be signed in 2026, that will commit them to consult each other at leader and minister level if either country’s security is threatened and to hold regular high‑level security dialogues.
Together, these arrangements mean much closer practical military cooperation (more joint exercises, training, and access arrangements), regular strategic consultations, and a clearer framework for working together on regional security challenges in the Indo‑Pacific.
“Deepening engagement with Pacific Island countries” usually means stepping up diplomatic, economic, and security cooperation with the small island states across the Pacific. In practice this typically involves:
• Security and policing: training and funding for local police, maritime surveillance and Coast Guard–style patrols, disaster‑response exercises, and help clearing unexploded ordnance from World War II. For example, the United States and Australia have been working with Pacific partners on maritime law‑enforcement patrols, disaster‑management capacity, and expanded defence and law‑enforcement cooperation with states like Papua New Guinea and Solomon Islands. • Infrastructure and connectivity: joint projects to build or upgrade ports, airports, undersea telecommunications cables, and digital networks (such as the Vaka cable to Tuvalu and other U.S.–Australia funded cables and port upgrades in PNG), often framed as providing “trusted” alternatives to projects backed by China or other external powers. • Economic, climate, and development support: aid and financing for climate‑resilience, disaster preparedness, health systems, and economic development—recognizing that climate change and natural disasters are core security issues for Pacific states. • Diplomatic and people‑to‑people links: more high‑level visits, regional summits and roundtables (such as U.S.–Pacific Islands Forum meetings), education and exchange programs, and agreements that signal political commitment to treat Pacific states as key partners.
Why this is significant for regional security: • Pacific Island countries sit astride key sea lanes and have large exclusive economic zones, making their security choices strategically important to larger powers. • Increased engagement by the U.S., Australia, and like‑minded partners is partly a response to growing Chinese security and economic activity in the region; closer ties aim to ensure that Pacific governments have alternatives and to prevent potentially destabilizing militarisation by outside powers. • Stronger local capacity for law enforcement, disaster response, and resilient infrastructure can reduce instability and make it harder for transnational crime, illegal fishing, or foreign military footholds to take root.
These are the kinds of initiatives Landau and Moriarty were referring to when they discussed joint efforts to “deepen engagement” with Pacific Island countries.