Leading article: A hawk lands in London

The Republican presidential nominee, Senator John McCain, made a flying visit to Britain yesterday, his penultimate stop on a tour that also took in Iraq, Jordan, Israel and France. While Senators Hillary Clinton and Barack Obama continue wounding each other in their bitter fight for the Democratic nomination, Mr McCain has the luxury of playing president-in-waiting on the world stage. He undoubtedly has more experience than either of the Democratic contenders on foreign affairs – a strength he has understandably sought to exploit. And in London it was refreshing to hear his elegantly diplomatic replies to questions, with their recognition of the price Britain had paid for its involvement in the Iraq war.

However, Mr McCain's foreign policy credentials may be less sound than he thinks. In Jordan he expressed concern that Iran had been training al-Qai'da forces in Iraq. One of his travelling companions, Senator Joe Lieberman, had to whisper a correction. The Iranian government is suspected of aiding Shia militants in Iraq, not Sunni al-Qai'da operatives.

It was a troubling error that might hint at larger shortcomings, whether they are to do with knowledge, experience or, dare one suggest, even age. A priority for the next US president, as for so many before, is bound to be the quest for peace and stability in the Middle East. It is not at all evident, however, that Mr McCain – who has suggested that US troops might remain in Iraq for 100 years – is as attuned to peace-making as he is to war. He supports the current US policy of isolating Hamas in the Israeli-Palestinian conflict. And he has proposed a new "League of Democracies" to bypass and perhaps eventually replace the UN.

There can be no question, of course, that Mr McCain was a deserving winner of the Republican nomination. And campaigning for the nomination is quite a different proposition from running for President – some of his more hare-brained foreign policy thoughts will probably die a death before the contest proper. In several other respects, his policy platform has much to recommend it – not least in his support for free trade, his permissive stance on immigration, and his support for measures to combat global warming.

It also needs to be recognised that there are hawks and hawks. And a McCain brand of hawkishness is likely to be less inflexibly, and ignorantly, ideological than George Bush's. In the end, too, the choice is for American voters to make. At least it is already clear that, whoever wins the Democratic nomination, they will face clear alternatives in November.

Both Mrs Clinton and Mr Obama have pledged to withdraw US troops from Iraq. Mr McCain's itinerary suggested a candidate who risked being stuck in old US ways of thinking.