Nato at 70 has its largest ever membership of 29 states (soon to be 30 when Northern Macedonia joins) but is probably in its weakest position for seven decades as an expression of a strong transatlantic alliance and partnership.
The United States under President Donald Trump has reinforced a distancing process from Europe at play since the end of the Cold War in 1989 as it now concentrates on Asia and demands more European military spending. At the same time it resents any erosion of its leadership, while Europeans increasingly question whether they share enough values and interests with the US to go to war in their defence.
Russian assertiveness, great power shifts in world politics, an unstable Middle East, international terrorism and new cyber threats combine to make European security more threatened and uncertain. That was the theme of Nato secretary general Jens Stoltenberg’s passionate address to the US Congress last week. Describing Nato as the longest lasting and most successful alliance in history, he insisted it still fulfils its original purpose in these changing circumstances to strengthen states and peoples on both sides of the Atlantic. He was able to cite more European spending in response to US urgings and was reassured by a recent overwhelming congressional vote in favour of Nato, despite Trump’s scepticism.
It is an unconvincing case because the continuing erosion of transatlantic values and interests increasingly undermines Nato's credibility and capacity to provide leadership in tackling this changing world. Trump's unilateral withdrawal from the Iran nuclear deal and the intermediate nuclear force agreement with Russia dilute solidarity and force the Europeans to act on their own behalf.
The same applies to the differing ways Europe and the US respond to China's emergence as a great commercial, economic and now geopolitical power. Suggestions that Nato should develop a common strategy on China resurrect older arguments about its role in Afghanistan.
Instead of strengthening Nato both sides are adjusting their worldwide security and defence commitments to better suit their respective interests. Nato will be less dominated by the US as the European Union develops a more coordinated defence capacity complementary to Nato's but decidedly more in line with its own position as a more determined global actor in politics and security.
Realistically, a European army is far away, however, because existing armed forces in the EU lack inter-operability, strategic capacity, and have fragmented budgetary and industrial structures. The Nato alliance is therefore likely to retain its role as an ultimate military guarantor of some shared interests and values.