Sen. Dianne Feinstein, D-California, said Sunday that North Korea poses a "clear and present danger" to the United States, in the wake of the country's second test of an intercontinental ballistic missile.

Feinstein said on "Face the Nation" that after spending time on intelligence and in briefings, she's "convinced that North Korea has never moved at the speed that this leader has to develop an ICBM to put solid fuel, to have an interesting launch device, and to have a trajectory which, as of the latest analysis, would enable it to go about 6,000 miles and maybe even hit as far east as Chicago."

"We can't have that," she added. "To me, it points out the danger in isolating a country, that they go to the science and the technical know-how to show their brute force, not to handle the isolation."

Sen. Dianne Feinstein on "Face the Nation," July 30, 2017 CBS News

Feinstein's comments come after President Trump tweeted Saturday about North Korea, saying he is "disappointed" in China for not doing enough in regard to the country -- a sentiment Feinstein echoed.

"I'm very disappointed in China's response, that it has not been firmer or more helpful," she said.

China has said that it shouldn't be held responsible for solving the nuclear standoff with North Korea, and that it doesn't hold the key to resolving the issue.

The intercontinental ballistic missile North Korea tested Friday flew longer and higher than the first one the country tested, according to its wary neighbors, leading analysts to conclude that a wide swath of the U.S. including Los Angeles and Chicago is now within range of Pyongyang's weapons.

Japanese government spokesman Yoshihide Suga has said that the missile flew for about 45 minutes -- about five minutes longer than the ICBM that was test-fired on July 4.

Following the launch, the U.S. conducted a missile defense test Sunday, using a Terminal High Altitutde Area Defense (THAAD) anti-missile system in Alaska. The U.S. Air Force launched a medium-range ballistic missile over the Pacific Ocean, and the THAAD system -- in Kodiak, Alaska -- "detected, tracked and intercepted the target," the U.S. Missile Defense Agency said in a statement Sunday.

Feinstein said "the only solution is a diplomatic one."

Feinstein added that she hopes incoming White House Chief of Staff Gen. John Kelly will be effective in beginning some "very serious negotiation with the North and stop this program."