U.S. Sen. Cory Gardner, R-Colo., introduced a resolution Tuesday that would put North Korea back on the list of state sponsors of terrorism as well as increase sanctions on the nation.

"The North Korean regime has a long history of belligerence toward the free world and brutal repression of its own people," Gardner said in a statement issued Tuesday. "It's clear that the Administration's current policy of so-called 'strategic patience' with regard to North Korea has been a failure, and it's time to change course. This resolution sends a strong message to the Administration that we must act quickly to address this major threat to the security of the United States and our allies in East Asia."

On Wednesday, North Korea claimed it has the ability to miniaturize nuclear weapons, which would allow it to attach a nuclear device to the top of a ballistic missile. U.S. officials responded with skepticism, saying they don't believe the North currently has such capabilities, according to CNN.

In his resolution, Gardner, chairman of the Subcommittee on East Asia, the Pacific and International Cybersecurity Policy, cited North Korea's "history of military threats, human rights abuses, and violations of international laws and agreements."

The bill asks the Obama administration to only restart negotiations with Pyongyang after "strict pre-conditions" have been established, "including a complete halt of Pyongyang's nuclear and ballistic missile programs, proliferation activities, military provocations, and a significant and verifiable improvement in the regime's human rights record."

According to Gardner, nuclear experts have estimated that North Korea currently has "as many as 20 nuclear warheads, and has the potential to possess as many as 100 warheads within the next five years." The resolution also mentions a 2014 U.S. Department of Defense report which states that the North "has proliferated nuclear technology to Libya via the proliferation network of Pakistani scientist A.Q. Khan."

In 2008, the Bush administration removed North Korea from the list of state sponsors of terrorism in an effort to save a nuclear deal that appeared to be on the verge of collapse, according to The New York Times. Pyongyang was originally added to the list in 1988 for bombing a South Korean airplane the previous year, killing all 115 passengers.

Since then, the North has continued to issue dozens of threats to South Korea and Western powers, and the three nuclear tests it's conducted have earned the country a number of U.S. and United Nations sanctions.

Cuba, Iran, Sudan and Syria are currently the only four countries on the list of nations that sponsor terrorism. President Obama decided in April to begin the process to remove Cuba from that list, a crucial step in Obama's efforts to restore diplomatic relations with the island nation.