Washington ? The Bush administration took a major step Friday toward building a new generation of nuclear warheads, selecting a design that is being touted as safer, more secure and more easily maintained than today’s arsenal.

A team of scientists from Lawrence Livermore National Laboratory will proceed with the weapons design with an anticipation that the first warheads may be ready by 2012 as a replacement for Trident missiles on submarines.

The new weapons program, which has received cautious support from Congress, was immediately criticized by some nuclear nonproliferation groups as evidence the government wants to expand nuclear weapons production – not move toward eliminating the stockpile.

Critics also maintain that it sends the wrong signal around the world by pushing a new warhead – although characterized as a replacement for existing ones- at a time the United States is trying to curtail nuclear weapons development in North Korea and Iran.

Some lawmakers agreed.

“The minute you begin to put more sophisticated warheads on the existing fleet, you are essentially creating a new nuclear weapon. And it’s just a matter of time before other nations do the same,” said Sen. Dianne Feinstein, D-Calif. “This could serve to encourage the very proliferation we are trying to prevent.”

Rep. Ellen Tauscher, D-Calif., chairwoman of the House Armed Services strategic forces subcommittee, expressed cautious support, but promised “a long evaluation process” in Congress to assure the warhead will do what is promised without future underground testing.

Nuclear underground tests have not been done since a ban in 1992.

The administration is asking for $119 million for the next fiscal year for design work.