For six months now, the Trump administration has been required to notify Congress within 48 hours any time Iran conducts a ballistic missile launch.

That requirement will expire at the end of 2019. But even though that's more than two years away, Democrats are already thinking about extending it for another three years.

Reps. Ruben Kihuen, D-Nev., and Seth Moulton, D-Mass., proposed legislation last week to extend the requirement all the way through 2022. The bill is a sign that even Democrats are worried, like Trump, about Iran's ongoing missile testing.

Members of both parties say those tests are a possible violation of the language related to the Iran nuclear agreement and something that Congress needs to know about as they happen, something Kihuen made clear when his bill came out.

"Despite condemnation from Congress, the administration and the U.N. Security Council, Iran has continued to expand its ballistic missile program, posing a threat to our national security and that of one of our closest [allies] in the region, Israel," he said last week.

But it's also a sign that lawmakers are still wary about President Trump's national security posture. Moulton offered the language last year as an amendment to the National Defense Authorization Act, and believes it's a good idea to extend it now in the midst of a new administration.

"As this provision expires at the end of 2019, Rep. Kihuen's bipartisan bill provides a necessary extension of this requirement at a time when the new administration has yet to release their national security strategy as required by law," he said.

In addition to a few other Democrats, the bill is also cosponsored by two Republicans: Reps. Doug Lamborn of Colorado and Randy Weber of Texas.

The idea of an extension was proposed after several Iranian missile tests, and nearly two years into the implementation of the nuclear agreement, formally known as the Joint Comprehensive Plan of Action. The JCPOA itself dealt with Iran's nuclear capability, but the United Nations resolution endorsing that agreement also included language on missile testing.

That language says Iran is "called upon" not to undertake activities related to ballistic missile, a weakening of a 2010 U.N. resolution that says Iran "shall not" participate in those activities.

Iran has since held a series of missile tests since the JCPOA was signed, which has led to complaints from both parties that Iran is trampling over the spirit of the new U.N. resolution.

Those tests, in October and November of 2015, March 2016 and January of this year, have been a constant source of tension among Republicans in particular, who didn't like the deal to begin with.

The Trump administration so far has indicated it will let the agreement stand, although Trump warned as a candidate that he may choose to push Iran hard to implement the agreement strictly. Iran's missile tests could be the issue that eventually tests that pledge, especially if they continue.

In the meantime, Congress, which historically has been quick to act to sanction Iran or hold votes to express its displeasure with Iran, wants to know everything the Trump administration knows.

"Our legislation will help ensure a long-term strategy and aid in deterring Iran's ballistic missile program and simply extends an existing requirement that the president notify Congress on Iranian ballistic missile launches or tests until December 2022," Kihuen said.