JAPAN'S new Prime Minister, Morihiro Hosokawa, yesterday set himself a timetable for reform which would have had more seasoned politicians gasping for breath in their smoke-filled rooms. Whether this is out of self-confidence, bravado or necessity is hard to say. Certainly the old men of the defeated Liberal-Democratic Party (LDP) will be tut-tutting with disapproval. However, Mr Hosokawa clearly hopes to ride the tide of public opinion in favour of serious political and economic reform. He deserves support. The politics of corruption and inertia that brought down the LDP must be tackled as speedily and ruthlessly as possible if the new government is to have any chance of succeeding. On the economic front, the sooner Japan shows that it has taken the fears of its trading partners to heart, the more likely it is to be able to fend off the most damaging effects of its own recession and the rising yen. Yet the sheer scale of the task he has set himself and his rash promise to implement sweeping political reforms by the end of the year must raise real questions about his ability to meet the standards he has set himself. United States President Bill Clinton started out with a similarly ambitious programme and dissipated so much energy, and political capital, in his first 100 days that his presidency faltered. Unlike Mr Clinton, however, Mr Hosokawa may have no choice. His eight-party coalition is united only in its commitment to political reform. It may never again be strong enough to tackle the entrenched interests linking politicians, bureaucrats and industrialists. But if he puts other tasks aside to take on the robber barons of the political world, he will lose the initiative in the battle against the corporate and agricultural dragons. Worse, he will find the economic might of the US, Europe and the currency speculators ranged against him. He has promised to stimulate domestic demand by sweeping away the stifling regulations and bureaucracy working against the interests of importers and consumers. But it is an indication of his domestic problems that he has declined to bow to pressure to allow rice imports. Even more than its Western competitors, Japan is committed to free trade only when for its own exports. It is doggedly protectionist in the face of others' cheaper products. Nevertheless, his promised reforms have prompted the US Federal Reserve to begin intervening in the currency markets to slow the rise of the yen and give Japan time to open its markets. Mr Hosokawa must now respond with effective action. If he fails to dominate his own country's conservatives, his Finance Minister's weekend prediction that Japan's trade surplus could help destroy the world economy could return to haunt him. If he has bitten off more than he can chew, it may be economic woes, not failure to introduce political reforms, that force him to resign by the end of the year.