Newsrooms and foreign ministries around the world are full of quotations, many of which have become detached from their original authors. One of the most frequently cited is attributed to Lord Palmerston, the 19th-century British prime minister. Addressing the House of Commons in 1848, he articulated a principle that remains central to diplomacy: Britain had no eternal allies and no perpetual enemies, only interests that were eternal and perpetual. It was a view of foreign policy that placed national interest above sentiment. Nearly two centuries later, his words remain among the closest things diplomacy has to a law of physics.
Palmerston was not simply being cynical. He was describing something every state, large or small, eventually learns: friendship between nations is not like friendship between people. It does not endure on memory or sentiment alone. It lasts as long as it serves a purpose. When that purpose changes, the relationship changes with it. No formal letter is necessarily required to announce the shift. It becomes visible in trade figures, troop movements and, sometimes, in who picks up the phone first after a crisis.
Geography makes this reality difficult to escape. In Prisoners of Geography, Tim Marshall argues that a country's mountains, rivers, coastlines and neighbours constrain its choices long before its leaders make them. Russia's exposed western approaches help explain its longstanding concern with strategic depth and buffer zones. Saudi Arabia's position between the Gulf and the Red Sea, amid a region of competing interests and shifting partnerships, helps explain why Riyadh has sought to diversify its security relationships. Geography does not care about loyalty. It concerns itself with exposure, access and defence.
Joseph Nye's concept of soft power adds an important dimension to Palmerston's realism. National interest is not simply a matter of tanks, pipelines and military bases. It also involves image, culture and the ability to persuade others to want what a country wants without coercion. A state's priority today might be a trade agreement; tomorrow, it might be a seat at a summit or the avoidance of diplomatic humiliation. Nye's contribution was to show that national interests extend beyond military and economic calculations, even if they remain closely tied to the pursuit of strategic advantage.
The past year has offered a vivid demonstration of these principles. The regional consequences of the war in Gaza, followed by Israeli strikes on Doha that challenged perceptions of security across the Gulf, have placed renewed pressure on governments accustomed to balancing competing relationships. States that had long hedged quietly between different security partners have had greater reason to consider making those calculations more explicit.
In September 2025, Pakistan and Saudi Arabia signed the Strategic Mutual Defence Agreement, under which aggression against one country would be treated as aggression against the other. The agreement prompted comparisons with Article 5 of the North Atlantic Treaty, which establishes NATO's collective-defence principle. The comparison is useful in explaining the pact's central provision, although the two arrangements should not be assumed to be identical in their institutional structures or practical obligations.
In August 2026, the relationship acquired a broader regional dimension when Saudi Arabia, Türkiye and Pakistan signed the Makkah Joint Defence Agreement. The pact provides that an armed attack against any one of the three countries will be regarded as an attack against all, while committing the signatories to closer defence cooperation. It brings together Saudi Arabia's economic weight, Türkiye's military capabilities and Pakistan's nuclear-armed status within a framework for collective defence.
The moment that purpose changes, the friendship changes with it, and nobody signs a formal letter announcing the fact. It just happens, quietly, in trade figures and troop movements and who picks up the phone first after a crisis.
The agreement's implications, however, will depend on how its commitments are implemented. Its signatories have described it as defensive and not directed against any particular country. That is the official position; the agreement's wider strategic significance remains a matter of interpretation. Some observers may read it as an effort to give regional states greater responsibility for their own security rather than relying exclusively on established external guarantees. Others may question how far the three countries' interests and threat perceptions will align when a crisis tests their commitments.
What makes such developments interesting is not simply the paperwork. It is the way states that have long spoken the language of brotherhood and solidarity also speak the language of self-preservation. These impulses are not mutually exclusive. Governments can value historical, religious and cultural ties while recognising that their security requirements may change. They rarely announce that an old arrangement no longer serves their interests. Instead, they establish new partnerships and allow their actions to communicate what their official statements leave unsaid.
This is not necessarily a flaw in how nations behave. It is part of the logic of survival at the level of the state. Individuals can sometimes afford loyalty that comes at a personal cost because they ultimately answer to their own consciences. Governments, by contrast, make decisions that affect millions of people. Leaders who consistently place sentiment above their country's perceived interests may find that the political consequences are severe.
Yet realism does not mean that alliances are meaningless or that trust has no place in international relations. Longstanding partnerships can create habits of cooperation, institutional ties and mutual expectations that make relationships more durable. The point is that such arrangements require continuing political commitment. Their existence does not eliminate the possibility of disagreement, nor does a shared interest in one area guarantee agreement in another.
Palmerston's observation endures because it captures an uncomfortable truth about diplomacy: relationships between nations can be genuine and consequential without being permanent. Shared history may bring countries together, but changing circumstances can alter their priorities. Geography shapes their vulnerabilities, economics defines some of their choices, and political leaders must constantly reassess the costs and benefits of cooperation. Friendship between nations is real while it lasts. It is simply never guaranteed to last.