The replicators easiest to build will be inflexible machines, like automobiles or industrial robots, and will require special fuels and raw materials, the equivalents of hydraulic fluid and gasoline. To build a runaway replicator that could operate in the wild would be like building a car that could go off-road and fuel itself from tree sap. With enough work, this should be possible, but it will hardly happen by accident. Catastrophic problems seem more likely to arise though deliberate misuse, such as the use of nanotechnology for military aggression. This seems to be a false alternative.
Many paths lead to nanotechnology, whether through chemistry, biotechnology, or physics.
Thousands of companies and dozens of countries are pursuing these paths and reaping benefits along the way. This competition ensures that it will be developed, regardless of whether any one group, country, or alliance favors it or opposes it. Ideally, the race for early breakthroughs will be won in a country or group of countries firmly under democratic control, where a free press and public scrutiny can help prevent abuse. Broadly-based international cooperation seems clearly desirable if we are to minimize the chance of friendly competition turning into hostile competition and then an unstated arms race. This makes continued friendship with Japan of great importance.