Inside the escalating war of words between the US and North Korea Trump's threat of "fire, fury" was not the first time things became heated.

 -- Although the rhetoric has become more heated this week, the war of words between U.S. and North Korean leaders has been intensifying for months.

Most recently, North Korean leader Kim Jong Un warned that the country would take "thousands-fold" revenge against the U.S.

President Donald Trump responded with a vow that any attack by North Korea "will be met with fire and fury."

Secretary of Defense James Mattis then warned the country's leaders against any actions that "would lead to the end of its regime and the destruction of its people."

Ahead, a timeline of both countries' statements and how the war of words escalated to where it is today.

Jan. 2

Trump tweeted about possible advancements in North Korean technology.

"North Korea just stated that it is in the final stages of developing a nuclear weapon capable of reaching parts of the U.S. It won't happen!" he wrote.

April 11

A statement from North Korea's Foreign Ministry was read on state television before a U.S. aircraft carrier group arrived in the region for a military exercise with South Korea.

"The United States' dispatching of its nuclear carrier task group in the waters off the peninsula proves that its reckless moves for invading North Korea have reached a serious phase. If the U.S. dares opt for military action, then North Korea is ready to react to any mode of war desired by the U.S.," the Foreign Ministry said, according to PBS.

April 18

North Korean Vice Foreign Minister Han Song Ryol said that an "all-out war" would result if the U.S. was "reckless enough to use military means," according to the BBC.

"If the U.S. is planning a military attack against us, we will react with a nuclear pre-emptive strike by our own style and method," he said.

April 24

During a lunch with ambassadors representing the member countries of the United Nations Security Council, Trump touched on how the group's policy toward North Korea needs to change.

"The status quo in North Korea is also unacceptable, and the council must be prepared to impose additional and stronger sanctions on North Korean nuclear and ballistic missile programs. This is a real threat to the world, whether we want to talk about it or not. North Korea is a big world problem, and it's a problem we have to finally solve. People have put blindfolds on for decades, and now it's time to solve the problem," he said.

April 28

April 30

In an interview with CBS, Trump called Kim a "pretty smart cookie" for having taken over after his father's death in 2011.

"I can tell you this, and a lot of people don't like when I say it, but he was a young man of 26 or 27 when he took over from his father, when his father died. He's dealing with obviously very tough people," Trump said.

"A lot of people, I'm sure, tried to take that power away, whether it was his uncle or anybody else. And he was able to do it," Trump said. "So obviously, he's a pretty smart cookie."

Early June

Foreign Policy reported that North Korea's Rodong Sinmun newspaper ran an article that made a not-so-veiled threat that New York could be within the range of the country's intercontinental ballistic missiles soon.

"The DPRK [Democratic People's Republic of Korea] is about 10,400 kilometers far away from New York. But this is just not a long distance for its strike today," the article read, according to Foreign Policy. "The U.S. is feeling uneasy, as this might be proven in practice. This is because its hostile policy will end in [futility] when the DPRK conducts the test-fire of ICBM capable of precisely striking any place on the U.S. mainland."

"Trump blustered early this year that the DPRK's final access to a nuclear weapon that can reach the U.S. mainland will never happen. But the strategic weapons tests conducted by the DPRK clearly proved that the time of its ICBM test is not a long way off at all," the North Korean article added, according to Foreign Policy.

June 30

During a press conference at the White House with South Korea's President Moon Jae-in, Trump said, "The years of strategic patience with the North Korean regime has failed. Many years and they failed. It's failed. And frankly, that patience is over."

"Together we are facing the threat of the reckless and brutal regime in North Korea. The nuclear and ballistic missile programs of that regime require a determined response. The North Korean dictatorship has no regard for the safety and security of its people or its neighbors and has no respect for human life. And that's been proven over and over again," he said.

July 4

Trump blasted North Korea on Twitter in response to its decision to launch a missile strike that day.

"North Korea has just launched another missile. Does this guy have anything better to do with his life? Hard to believe that South Korea and Japan will put up with this much longer. Perhaps China will put a heavy move on North Korea and end this nonsense once and for all!"

Aug. 7

North Korea said in a statement that it would take "thousands-fold" revenge against the United States in response to the latest round of international sanctions over its nuclear program.

The statement came through a state-run media outlet, the Korean Central News Agency, two days after the U.N. Security Council unanimously approved sanctions to penalize the regime for its escalating nuclear program and missile launches.

North Korea slammed the penalties — which could slash the country's $3 billion in export revenue by a third — as a "violent infringement of its sovereignty" and part of a "heinous U.S. plot to isolate and stifle" the country.

The sanctions ban North Korea exports of coal, iron, lead and seafood products, estimated to be worth $1 billion a year.

But North Korea asserted the punishment will not lead it to change course.

"It's a wild idea to think the DPRK will be shaken and change its position due to this kind of new sanctions formulated by hostile forces," the government said in its statement.

Aug. 8

Trump warned North Korea against making any further threats against the U.S.

"North Korea best not make any more threats to the United States. They will be met with fire and fury like the world has never seen. He has been very threatening — beyond a normal statement — and as I said, they will be met with fire, fury and, frankly, power the likes of which the world has never seen before," Trump said, referring to North Korea's statement about taking revenge.

Aug. 9

North Korea threatened to strike the U.S. territory of Guam in a statement distributed by its state-run news agency.

The statement said that the North Korean military is reviewing a plan to create an "enveloping fire" around Guam, in the Pacific Ocean about 2,100 miles from North Korea.

Later that day, Secretary of State Rex Tillerson, in Guam for a refueling stop on his way back to the U.S. from a regional summit in the Philippines, dismissed North Korea's rhetoric about attacking the island.

"I do not believe that there is any imminent threat," he said. "Americans should sleep well at night."

In the statement released by the Department of Defense, Mattis didn't mince words, cautioning North Korea that its actions "will continue to be grossly overmatched by ours and [it] would lose any arms race or conflict it initiates."

He added that Kim should "take heed" of the U.N. Security Council's "unified voice," referring to the sanctions issued against the nation, and called for the country to "cease any consideration of actions that would lead to the end of its regime and the destruction of its people."