A missile control treaty violated by one signatory is little better than no treaty at all. And when U.S. officials make it clear they are willing to overlook some violations, the danger is that our "partner" - in this case, Russia - will be emboldened to break other provisions of the pact.

U.S. and Russian negotiators are busy attempting to come to an agreement on a new strategic arms reduction treaty. It would replace the START pact negotiated about 15 years ago. The deadline for agreement on a replacement is Dec. 5.

But some members of Congress are concerned that a new treaty may not be worth the paper on which it is written. That is because there is evidence Moscow already has violated the current START agreement.

During a recent speech, Sen. Jon Kyl, R-Ariz., said the Russians have developed a new multiple-warhead missile in violation of the existing treaty. Kyl and other lawmakers want to know more about the violation. But according to a published report, the State Department is not providing it.

In a letter to Kyl, Assistant Secretary of State Richard Verma said he could not answer the senator's questions - because of negotiations on a new treaty. He added that President Barack Obama's administration has "committed ourselves fully" to negotiating a new treaty.

We hope that commitment is not a "success at all costs" one in which the goal - arms control - is subordinated to the political desire for a treaty. Kyl and other lawmakers should press for answers.