The world is hardly becoming a safer place these days. Missile threats are proliferating at a disturbing rate in places such as North Korea the danger from the North’s nuclear program is now at an ‘alarming’ level,” The Washington Post recently noted. So now is hardly the right time to be tying our hands on missile defense.

Yet that seems to be exactly what the Obama administration is doing. Case in point: the New START arms-control agreement between the United States and Russia.

The treaty can’t go into effect until the Senate consents to its ratification. There’s a push now, spearheaded by Sen. John Kerry (D-Mass.), to get lawmakers to vote on New START during the “lame duck” session of Congress that will occur after the Nov. 2 elections.

According to the Obama administration, senators have nothing to worry about when it comes to missile defense. New START, the White House insists, won’t limit our options in this vital area of our defense, including the construction of any space-based components.

At least half a dozen senators, however, have serious doubts about this. They’re concerned about a side agreement that the administration is on the verge of completing with Russia -- an agreement that could very well compromise our ability to deploy an effective missile defense, regardless of what the treaty itself says.

Six Republicans -- Sens. Jeff Sessions (Ala.), James Inhofe (Okla.), David Vitter (La.), John Cornyn (Texas), Roger Wicker (Miss.) and John Thune (S.D.) -- have sent a letter to Secretary of State Hillary Clinton about the side agreement. Their request? Make available to the senators the documents and records regarding the negotiations of this agreement. And they’ve made it clear that these details need be in their hands before the full Senate takes up New START.

It should be noted: There’s nothing wrong with the administration negotiating a side agreement on the treaty. Indeed, it’s to be expected; such agreements are common when treaties like this are being hammered out. It’s the content of the side agreement -- especially when it comes to the sensitive area of missile defense -- that’s at issue here.

If the administration has nothing to hide on that score -- if the side agreement contains nothing that would jeopardize our ability to field an effective missile defense -- making the details of the negotiations available to the senators shouldn’t be a problem. Right?

Well, maybe not. After all, Russian leaders have certainly voiced their opposition to a U.S. missile defense. And the Obama administration, according to Heritage Foundation defense expert Baker Spring, “offered a unilateral statement to Russia at the time New START was signed that states in effect that the U.S. intends to limit its missile defense program so that it will not affect the strategic balance with Russia.”

In short: We’ll make sure U.S. missile defenses can’t shield us from the type of long-range ballistic missiles that Russia possesses -- the same type of missiles that countries such as North Korea are working feverishly to acquire. To make Russian leaders happy, we’ll make ourselves vulnerable to attack by others. What sense does that make?

But there’s an easy way to settle the matter and ensure, as the White House claims, that New START does not “contain any constraints on testing, development or deployment of current or planned U.S. missile defense programs.” And that’s to make the details of the side agreement available to the senators who wrote to Secretary Clinton.

There are many areas of our government that would benefit from more transparency. Surely our national security -- a matter, literally, of life and death -- tops the list.

Ed Feulner is president of The Heritage Foundation.