President Bush's proposed missile defense network has suffered a setback in Congress. A key Senate committee has voted to limit tests of the system and cut its funding.

The Senate Armed Services Committee action is only the first step in a long process. But it clearly shows the concern many Democratic lawmakers feel about the issue, especially about violating the Anti-Ballistic Missile, or ABM, treaty with Russia.

Under a bill approved Thursday by the Democratic-led panel, Congress would have to authorize any missile defense test that would breach the ABM accords. If the House and Senate reject a test, Mr. Bush could not spend money to carry it out. The Armed Services chairman, Democratic Senator Carl Levin, argues the restrictions are justified.

"Congress has a responsibility here because the stakes are very high, to know what we are voting on," he said. "To know whether a test for which funding is sought from the public treasury, and which Congress alone can appropriate and authorize, whether or not those funds are being used to test in a way which conflicts with a major arms control agreement."

The measure would not stop Mr. Bush from withdrawing from the ABM treaty outright if he eventually chooses. But Republicans warn the limits could still tie the president's hands and in the meantime would weaken his position in talks with Moscow, which strongly wants ABM to remain in force.

Senator John Warner, the top Republican on the Armed Services panel, vows the curbs on testing will never become law. "The intensity, the feeling among the Republicans [on the committee] was so great that we voted unanimously not to report the bill out [to reject the bill]," he said. "The vote was 13 Democrats to report out, 12 Republicans in the negative."

The committee has also voted to trim the president's missile defense budget request by one-point-three billion dollars. The program would still get about $7 billion in the coming fiscal year that begins Oct. 1.

The overall Pentagon budget is part of a larger battle over government spending, which will dominate the rest of this year's congressional session.