Sen. Dan Sullivan, R-Alaska, said on Friday that the U.S. must upgrade its missile defenses following the newest North Korea test launch of an intercontinental ballistic missile.

More interceptors in Alaska and sensors in space could protect not only his state but major American cities such as New York and Los Angeles as Kim Jong Un's regime moves ever closer to a nuclear-tipped missile capable of hitting the U.S. mainland, said Sullivan, who is a member of the Senate Armed Services Committee.

"While I am hopeful that a diplomatic solution will ultimately prevail, the United States cannot and will not allow an irrational dictator to have a capability that threatens millions of American lives," he said.

The Pentagon confirmed the second North Korean launch of an ICBM on Friday but did not release flight data. Some independent experts estimated the missile was capable of traveling over 6,000 miles, far enough to reach California.

Sullivan is among a group of Senate and House lawmakers pushing for more missile defense spending in the 2018 defense budget.

His legislation calls for up to 28 new ground-based missile interceptors at Fort Greely, Alaska, and invests in developing a layer of space-based sensors to provide better missile tracking. It is now part of the National Defense Authorization Act, which is awaiting a floor vote in the chamber.

The House Armed Services Committee has also proposed a boost to missile defense in its NDAA bill, including $30 million in seed money to start studying and prototyping space-based missile interceptors similar to a system first envisioned by former President Ronald Reagan in the 1980s.

Rep. Mac Thornberry, R-Texas, the committee chairman, said the launch amplifies the growing danger and means the U.S. needs to expedite its efforts to protect the country.

"We need a stronger approach on a faster timeline now," Thornberry said.