Still arm wrestling? [By Jiao Haiyang/China.org.cn]

With the new START treaty between the United States and Russia coming into effect on Saturday, it is to be hoped that our planet is one step closer toward the long-cherished dream of achieving a world free of nuclear weapons.

The pact, built on the 1991 START, or Strategic Arms Reduction Treaty, limits each side to 1,550 deployed strategic warheads, down from 2,200, or a cut of 30 percent. The two nuclear superpowers will limit their deployed strategic launchers and heavy bombers to 700.

Negotiated last year, the new START was approved by the US Senate in December and the Russian parliament last month. It has been widely perceived as the most comprehensive nuclear disarmament pact in 20 years and it marks a new stage in international nuclear arms control and denuclearization.

The new START also re-establishes a monitoring system that ended in December 2009 with the expiration of the first START. It will allow each side to visually inspect the other's nuclear capability to verify how many warheads each missile carries.

It is gratifying to see that the two nuclear giants are taking concrete measures to slash their nuclear arsenals and that, as US Secretary of State Hillary Clinton said, they have taken another step to ensure the nuclear button "will never be pushed".

However, it should remain clear that even if the two powers carry out the treaty to the letter they still possess 90 percent of world's nuclear weapons.

In fact, the promised cuts in the treaty are not as dramatic as they might appear as each missile carries more than one warhead. The rules for counting warheads also reportedly contain a loophole. While each warhead on a ballistic missile is counted as one warhead, a heavy bomber is counted as carrying only one warhead even though it may carry many.

Also the agreed ceilings apply to deployed warheads, not to warheads in storage. A warhead could, in theory, be put into storage, and then redeployed when needed.

Some have suggested the new START is merely a symbolic gesture or political showcase. To dispel such suspicions, Washington and Moscow should continue their nuclear disarmament efforts and use the new START treaty as a springboard for cooperation on security issues.

With more than 23,000 nuclear weapons in the world and a few countries vying to join the world's nuclear power club, the prospects for world nuclear security are in reality probably as bleak as ever.

The United States and Russia, as the world's two nuclear superpowers, shoulder great responsibility and should build on the momentum they have generated so far and take continuous steps to achieve deeper reductions in their nuclear arsenals.