London — Are Australia and New Zealand steadily drifting away from their alliance with the United States, and will nuclear weapons be the catalyst that could eventually break down defense confidence among the three nations? The issue has become urgent, now that New Zealand has banned visits to its ports by nuclear-capable ships and Australia has refused to cooperate with the US on tests of the MX missile. But strains between the US and its antipodean allies are nothing new, and it is hard to see how the ANZUS (Australia-New Zealand-US) alliance, which has existed for 33 years, can remain unaffected.
Outright rejection of nuclear weapons by New Zealand Prime Minister David Lange, and the less hostile but widely supported nuclear standpoint of Australia's Bob Hawke, have been latent in the two countries' politics for nearly two decades. Among Labor politicians these reservations seem unlikely to disappear.
In Washington, confidence that Australia and New Zealand would remain unquestioning acolytes within the ANZUS fold has been encouraged by the ability of conservative-minded governments to dominate politics for much of the postwar period.
In post-1949 Australia, the rule of the Liberal-National coalition was broken only in 1972 with the election of a Labor government. But that was short-lived, and Australia soon settled down again to implicit loyalty to the US and acceptance of its broad strategic goals in the Pacific.
The New Zealand postwar period was not dominated quite so completely by governments with a conservative orientation, but the same tendency was present. New Zealand, like Australia, contributed troops tothe Vietnam war, just as they had done in Korea.
Even in those days, however, New Zealand set a stricter limit than did Australia on military commitments in Asia, and the commitments were made against a loud chorus of political opposition.
The impetus for New Zealand's attitude was not exclusively anti-Americanism. The Labor government that came to power in 1972 opposed French nuclear testing in the South Pacific by sending a naval vessel into the test area with a Cabinet minister aboard.
But since then, in both Australia and New Zealand, antinuclear sentiment has focused more sharply on US actions. Much the same political forces that criticized France now focus on the US, arguing the South Pacific should remain nuclear-free.
Lange's ban on nuclear-capable ships is rooted in this conviction. The prime minister, who came to office last July, campaigned on an antinuclear ticket, and his supporters claim that two-thirds of his country's voters uphold him in his current stand against nuclear visits.
Across the Tasman Sea, Mr. Hawke's antinuclear left wing is less influential, but it has to be reckoned with.
A key element in nurturing attitudes that run counter to the declared strategic interests of the US has been the need for Australia and New Zealand to establish closer working relations with neighbors in the South and Southwest Pacific, where antinuclear sentiment is strong.
Adversary domestic politics have also played their part in this process, notably in New Zealand, where the former conservative prime minister, Robert Muldoon, was so outspoken in his pronuclear views that he set up contradictory attitudes in Labor. Had not Muldoon been so determined, it is uncertain that Lange would be so opposed to the visits of US nuclear ships now.
In Australia, there is a greater sense of the necessity for protection under the US nuclear umbrella. The country is host to at least three vital American defense communication stations, and any attempt to renegotiate the strategic relationship between Canberra and Washington would be complex and controversial.
But so long as Labor governments remain in power in the two nations, there will be distinct limits to their cooperation with the US on matters of nuclear defense.