Iran is a country with a long, rich and proud history. Iran is also a country with evident nuclear ambitions. Despite assertions by the regime otherwise, the country appears to be aggressively progressing towards achieving a nuclear arms capability. Such a scenario would have grave consequences for the U.S. and our allies in the Middle East, as well as the world at large. It is imperative that the policy of the United States be to stop and reverse Iran’s march to a nuclear bomb.

Since 1979, the U.S. has sought to dissuade Iranian nuclear ambitions through the use of economic and military sanctions. These sanctions are not in place to punish the Iranian people, but to change the calculus, and thus the decision making, of the Iranian Supreme Leader. While there are increasing indications that the sanctions are having the desired effect, there is also increasing concern that the time available to stop Iran’s nuclear pursuits is running out.

That is why 78 members of the Freshman Class of the 113th Congress stand together as Democrats and Republicans committed to ensuring that Iran does not succeed in its pursuit. In a letter to President Obama, we asked that, while his Administration pursues diplomatic possibilities, it also continue to enforce sanctions on the Iranian regime. As long as the Iranians accelerate their efforts toward nuclear capabilities, we should accelerate the enforcement of the sanctions. We must continue to provide targeted prohibitions and seek to limit the ability of Iran to expand its income streams away from sanctionable oil and petroleum products.

Last month, President Obama and Iranian President Hassan Rouhani spoke directly by phone, the first such contact in more than three decades. We hope this can lead to a successful diplomatic resolution to the Iranian nuclear issue, as a negotiated outcome has always been the preferred outcome. Sadly, however, since President Rouhani’s election there is substantial evidence to suggest that at the same time Iran is pursuing a new public relations campaign, Tehran is also accelerating its nuclear programs. The most recent International Atomic Energy Administration (IAEA) report released in August indicates that Tehran continues its large-scale installation of advanced, higher-speed centrifuges that will enable significantly more rapid production of weapons-grade uranium. This greater number of more efficient machinery moves Iran closer to reducing its “breakout” window to a few weeks, instead of the several months currently estimated for Iran to build a weapon.

While the words coming from Teheran may be positive, what matters are actions. Unfortunately, history has shown that Iran often uses the cover of diplomacy to advance its nuclear weapons program. Iran is too close to a nuclear weapon for us to be deceived and swayed by false promises. Rhetoric as a dilatory tactic must not be allowed.

In our view, the U.S. must continue to strengthen the enforcement of economic and political sanctions until Iran dismantles its nuclear program and stops its pursuit of an enrichment capability. We must stand prepared to increase the scope and pace of current sanctions if Iran continues its nuclear activity. We should pursue construction and foreign exchange penalties to prevent Iran from evading existing energy and financial sanctions. And, as the President has done, we must continue to make clear that the use of military force is an option if Iran fails to shut down its nuclear program.

Iran must know that it will not obtain a nuclear weapon under any circumstances. Allowing Iran to acquire a nuclear weapons capability would directly threaten the United States, our interests and our allies. The world is watching and history will judge our actions on Iran with one simple question – did we stop Iran’s nuclear weapons program?