A North Korea sanctions bill awaiting approval in the U.S. Senate targets not only banned and illicit activites, but also Pyongyang's trade in minerals and precious metals, a key source of hard currency for the regime, the legislation's main sponsor said Thursday.

Sen. Cory Gardner (R-CO), chairman of the Senate Foreign Relations Subcommittee on East Asia and Pacific Affairs, made the remark in an interview with Yonhap News Agency, stressing the Senate is committed to having tough sanctions on the desk of President Barack Obama to "stop this forgotten maniac once and for all."

"The main point of the bill obviously is a mandatory sanctions regime," Gardner said. "This would be a much harsher, much stiffer sanction regime as it automatically puts people under sanctions for money laundering activities, for trying to deal with luxury goods in North Korea."

Last week, the House of Representatives passed a North Korea sanctions bill overwhelmingly in a 418-2 vote. Gardner said his legislation addresses what the House bill doesn't, including the "issue of minerals and coal, precious metals."

"If those are being used for the purpose of either funding or supplying proliferation activity that is sanctioned by the bill, then that would create not only sanction in North Korea but second-order sanctions around the globe for that," he said. "This bill goes very far and I think is the right direction we need to put the pressure on North Korea to stop what it is doing when it comes to nuclear weapons."

Gardner introduced the legislation in October, together with Sens. Marco Rubio (R-FL) and Jim Risch (R-ID). It is one of two North Korea sanctions bills in the Senate and calls for sanctions on the North for its nuclear and missile programs, human rights abuses and cyber attacks.

The Senate Foreign Relations Committee is scheduled to hold a markup session on Jan. 28 and the legislation will reach the Senate floor around late this month or early next month, he said.

"There is unanimous agreement that we denuclearize the North Korean regime and that we do so peacefully and we believe that the legislation that we can put forward from Congress will be a part of that solution to make sure that North Korea no longer possesses the nuclear weapons that threaten our great allies like the ROK and Japan-the US," the senator said.

"Clearly, we've already got a date, the commitment from the chairman of the Foreign Relations Committee to move forward and then securing floor time to make sure that we have the vote in the Senate and to get this onto the president's desk," he said.

Gardner is one of a handful of leaders in Congress who have consistently called for greater attention to the North's nuclear and missile threats as well as its human rights abuses when the Obama administration has been preoccupied with other problems like Syria, Russia and the Islamic State group.

"In many ways, North Korea has been this forgotten threat," Gardner said during the interview. "The people's attention has been drawn to the Middle East-and rightfully so. There's very dangerous conditions, terrorism, developments in the Middle East we have to pay attention to, but that doesn't mean we take our eye off of the forgotten maniac in North Korea."

Gardner criticized Obama's North Korea policy, known as "strategic patience," for failing to curb the North Korean threats.

He said there is "bipartisan recognition" that strategic patience has been a "strategic failure" and the U.S. should have a new approach.

The senator also pointed out that three of the North's four nuclear tests took place under Obama.

"Unfortunately, strategic patience is ignoring it. It's one of disengagement and waiting and seeing and trying to wait them out.

Well, it hasn't worked. We know that they have continued to develop and indigenize their ballistic missile program," he said.

"We have to have a new policy," he said "This sanctions regime that makes it from a discretionary sanction to a mandatory sanction, that we focus on human rights developments and that we put a strategy in place to stop this forgotten maniac once and for all."

Gardner said he has received briefings from senior administration and intelligence officials about the North's self-proclaimed hydrogen bomb test, but there has been no definitive conclusion yet about what kind of a device was detonated.

Noting widespread skepticism about the North's claims, the senator warned against downplaying the test, stressing that the North could have tested a device boosted by hydrogen, which he said still makes the device technically an H-bomb. That, if true, would represent "a significant step forward," he said.

Gardner also said he supports the deployment of a THAAD missile defense unit to South Korea, saying the threat from North Korea shows the system is "needed now more than ever." He also said that South Korea should act in the best interest of its national defense, regardless of Chinese complaints.

He also hailed last month's landmark agreement between South Korea and Japan on resolving the issue of Japan's wartime sexual slavery, stressing that the deal should be followed up with action.

Cooperation between the U.S., South Korea and Japan is critical to ensure peace on the peninsula and beyond, he said.

Gardner also dismissed Republican presidential front-runner Donald Trump's unfounded accusations that South Korea is getting a defense free-ride from the U.S. and pays almost nothing for the upkeep of about 28,500 American troops stationed in the country.

"We have a great relationship that has been taken on -- a lot of it on the shoulders of the South Korean people, who are paying a tremendous amount for this security. It's important to the U.S. that that remains in place. It's important that the security remains in place," Gardner said.

"It is certainly a mutually beneficial agreement that we are there to provide protection to a great ally. Donald Trump probably needs to look at it a little more," he said. (Yonhap)