U.S.-U.K. RELATIONS AFTER BLAIR

Although he's likely to stay in power for another year, British Prime Minister Tony Blair is on something of a valedictory tour - making foreign-policy speeches at home, in Australia and (as soon as this week) in the United States.

But even if Blair makes a 10-year run of it, and remains on the job through May 2007, we Yanks should be looking at what will happen when Gordon Brown moves into No. 10 Downing Street.

Chancellor of the Exchequer Brown, Blair's near-certain successor, has done a solid job reinvigorating the British economy based on free-market principles. But he's largely a foreign-affairs mystery, which leaves very open the question of how he'll manage the British-American "special relationship."

Most observers believe Brown won't diverge significantly from Blair's foreign policy, but it's likely that he'll edge left - toward the Labor Party's base - and away from positions that are now highly unpopular in Britain.

That also means a move away from President Bush, who has worked well - and closely - with Blair. That may mean trouble ahead on a number of vital issues, including Iran, nuclear policy, and, even, NATO.

It's not unusual for a country's "treasury secretary" to say little about foreign policy matters, but Brown has been especially mum.

We do know that Brown takes world poverty seriously, supporting efforts to double aid to the Third World, and to get other governments and institutions like the World Bank/IMF to write off vast amounts of bad Third World government debt. The issue was big at last year's G-8 summit in Scotland. Brown went so far as to call that drive "a modern Marshall Plan" for the developing world.

What about Iraq? Brown played little apparent role in Blair's prewar decisionmaking - indeed, the British press reported that he was thoroughly marginalized. In the end, he publicly backed Blair on the war. But, having been skeptical from the outset, he's surely supportive of the recent, quiet British drawdown in southern Iraq to 7,800 troops -and, undoubtedly, beyond.

Brown is a former academic , so it's not really surprising that he seems to favor the "soft" power of financial institutions over the "hard" power of military campaigns in international affairs. On the evidence, he doesn't much believe in pre-emption and military intervention. In the wake of the Iraq experience, he's likely to be even more reluctant in the future.

Brown has said little about the transatlantic relationship with the United States, but he follows Blair in being both a strong Atlanticist as well as Unionist (i.e., European Union) - but skeptical of the Euro, the still-young European single currency. Brown even holidays in New England - but it's often with Democratic strategist friends, which surely taints his views of Bush.

So, Brown, in general, seems to be a mixed bag in terms of U.S. interests. But there are other important areas where rough patches are likely to crop up that would strain U.S.-U.K. ties:

Iran: Tehran's in blatant violation of its treaty commitments not to seek a nuclear-weapons program. The current U.S./UK/EU approach is to push for U.N. economic sanctions to get the mullahs to reverse course. Brown seems unlikely to challenge that consensus - but if Tehran remains defiant, he's a poor bet to support any military action.

Deterrence: In the next few years, Britain must decide whether to replace its Trident submarine-based nuclear deterrent. The current force of four "boomers" goes out of service in 2024. Brown will be under pressure from Labor's pacifist wing to disarm - a move that would symbolize, and hasten, the end of Britain's traditional, steadfast (and Yank-friendly) leadership in world affairs.

NATO: This fall's NATO summit in Riga, Latvia, will be a turning point for the alliance's future - especially its role outside Europe. The United States is broadly looking for NATO to do more. Brown, always tough on defense budgets and less interventionist, is likely to go slow on expanding NATO's role.

Overall, Brown isn't likely to be a disaster for U.S. foreign policy - but an initial distancing from Washington is likely, both to keep the party base happy and to boost his poll numbers, where in some cases he's less popular than Blair.

Nevertheless, if Brown gets the nod from his party (and historically that's no sure bet), he's unlikely to end the special relationship with the U.S. But under Brown, it's possible the relationship won't be so special after all - and that would be a bloody shame for both London and Washington.

Peter Brookes is a Heritage Foundation senior fellow. His book, "A Devil's Triangle: Terrorism, WMD and Rogue States," is just out.