Twenty-four years ago, Pres. Ronald Reagan traveled to Reykjavik, Iceland, to negotiate an arms-control treaty with the Soviet Union. When the Soviets insisted that the treaty must limit America’s missile-defense program, which was designed to guard against intercontinental ballistic missiles, Reagan walked away. He later explained, “We prefer no agreement than to bring home a bad agreement to the United States.”

Apparently times have changed. President Obama wants to jam a deeply flawed arms-control treaty with Russia, known as New START, through a lame-duck session of the Senate just to rack up an accomplishment before the end of the year.

New START misses one opportunity after another to maintain a stable nuclear relationship between our two countries. To remedy this will require significant time on the floor of the Senate. Trying to force it through without ample time for debate and amendments would amount to a Christmas gift to the Russians.

First and foremost, missile defense remains a major point of disagreement between the United States and Russia, and this treaty only makes the situation worse. Russia has threatened to withdraw from the treaty if we expand our missile-defense capabilities. It made a similar threat when the original START was completed under the first President Bush. At that time, President Bush said directly that our missile-defense activities have no bearing on Russia’s arms-control obligations. I am concerned that President Obama’s response to the Russian threat this time is weaker.

Moreover, the treaty contains a direct limitation on U.S. missile-defense-system deployments. Why does a treaty ostensibly about offensive weapons mention missile defense at all? It appears to have been included only to appease Russia.

Treaty proponents argue that New START furthers the legacy of Ronald Reagan’s vision of a world without nuclear weapons. Let’s be clear about one thing: President Reagan never would have sacrificed missile defense on the altar of arms control.

Second, Russia has an estimated ten-to-one advantage over the United States in tactical nuclear weapons, a situation that was not addressed at all by New START. These are the kinds of weapons that are most susceptible to theft or diversion to emerging threats, including terrorists and rogue nations such as North Korea and Iran. They are the weapons Russia has reportedly moved closer to our NATO allies. One of our top goals going into negotiations on this treaty should have been to close that gap, so why wasn’t it mentioned? Because the Russians didn’t want to talk about it.

Third, treaty proponents argue that the Senate must rush consideration of New START because we now lack the ability to verify what Russia is doing. This would make sense if the verification provisions in the treaty were something to be celebrated and worth rushing into place.

However, New START’s verification provisions are much weaker than what we had under the previous treaty. This is a serious concern, because experts say Russia has essentially cheated in one way or another on pretty much every major arms-control treaty to which it is a party.

What’s more, as the expiration date of the previous START approached last year, the administration promised it would come up with some sort of “bridging agreement” to keep verification efforts going until the new treaty could be ratified. The parties never finished that agreement, and so any verification gap has been created by the administration.

The Senate has a responsibility to consider treaties thoroughly to ensure they are in our country’s best interest. It should not rush its duty now to make up for the Obama administration’s mistakes. We lose nothing by postponing consideration of this treaty until the new Congress convenes in a few weeks.

This flawed treaty has too great an impact on America’s national security to be taken lightly or rushed for the sake of political pride.

— South Dakota senator John Thune serves as chairman of the Senate Republican Policy Committee.