At the State Department after a meeting with the Foreign Minister of Turkey, Rice said she would not want to speculate on the motivations of North Korea over the missile tests or firings.
The US' strong assertion comes days after President Donald Trump pledged to answer further aggression from North Korea with "fire and fury".
Here are some of the images from the parade.
North Korea has been suspended from the International Olympic Committee (IOC) until the end of 2022, meaning it will miss out on the Beijing Winter Games, after failing to send a team to the Tokyo Olympics, IOC President Thomas Bach said on Wednesday.
India's top paddler prevailed over a tough field to win the singles title at the 21st Pyongyang Invitational tournament.
North Korea's representative at the International Olympic Committee said the country expects to send a figure skating pair to compete at the Pyeongchang Winter Olympic Games in South Korea next month.
The disgraced scientist only helped North Korea in enriching uranium.
The Japanese government warned the people in northern Japan to prepare for a potential incoming missile from Pyongyang.
North Korea made its decision to pull out of Tokyo at a meeting of its Olympic committee and Sports Minister Kim Il Guk on March 25, the ministry said on its website.
North Korea had stopped the nuclear reactor, located within the nuclear complex in Yongbyon, north of Pyongyang, late last year, with no signs of reprocessing activities there anymore.
Earlier, United States Secretary of State Rex Tillerson urged the international community to increase pressure on North Korea, saying that failing to do so would bring 'catastrophic consequences'.
CNN quoted a South Korean defence official as saying that the missile launch was carried out from North Korea's Sinpo region in South Hamgyong Province.
After Pyongyang tests a missile potentially capable of reaching the US, Dr Rajaram Panda explores the realistic -- and peaceful -- options before Donald Trump and the international community at large.
On Sunday, North Korea said it detonated a hydrogen bomb designed for a long-range missile and called its sixth and most powerful nuclear test a "perfect success", sparking world condemnation and promises of tougher US sanctions.
In the Indo-Pacific's new era -- where perception shapes reality faster than treaties -- the real entrapment is not of China or the United States. It is the test Japan has set for itself -- and whether partners like India, acting as balancers rather than accelerants, can help ensure that the story ends in stability, points out Varun Arya.
"While I greatly appreciate the efforts of President Xi & China to help with North Korea, it has not worked out. At least I know China tried!" Trump said in a tweet which came hours before the US and China were set to meet in Washington to talk about North Korea.
Mattis' remarks came after Trump warned that 'appeasement' won't work with Pyongyang.
Asserting that the United States is ready with all its contingency plans to defend itself and its allies from any misadventure from North Korea, Defence Secretary Chuck Hagel has warned that the isolated nation was "skating very close to a dangerous line"."North Korea has been, with its bellicose rhetoric, with its actions, skating very close to a dangerous line," said Hagel with Army General Martin Dempsey, chairman of the Joint Chiefs of Staff.
North Korea had recently called on its citizens to be ready for a nation-wide struggle against 'war thirsty' Trump.
The White House has maintained that this is "not the time to talk" to North Korea, which has been carrying out ballistic missile test.
A seismic tremor recorded in an area around North Korea's known nuclear site on Friday is suspected to be a nuclear test, says South Korea.
The new sanctions imposed on North Korea by the United Nations Security Council would bite hard, US ambassador to the UN Susan Rice said on Thursday after the passage of an unanimous resolution in this regard.
India on Wednesday reacted strongly to the rocket launch by North Korea, saying the 'unwarranted action' by that country has adversely impact peace and stability in the Korean peninsula.
The 15-member body strongly condemned North Korea's ballistic missile launches.
The report of Kim's illness started doing rounds following his absence at the Kumsusan Palace of the Sun in Pyongyang on the birthday of late state founder and his grandfather, Kim Il-sung, earlier this month.
North Korea overcame Japan 5-3 via the tie-breaker to lift the AFC Youth Championship for the second time after a breathtaking final.
North Korea will take part in the next two Olympic Games in Japan and China, International Olympic Committee President Thomas Bach said on Saturday after meeting North Korean leader Kim Jong Un in Pyongyang.
South Korea Defense Ministry spokesman Kwon Ki-joon, said that "several projectiles" flew about 1,000 kilometers.
Indications of this came when Kim Jong Il skipped the parade commemorating the 60th anniversary of the foundation of North Korea on September 9. However, North Korean officials were quick to dismiss speculations about Kim Jong's health as baseless rumours spread by the West.
UN Secretary General Ban Ki-moon denounced the launch and asked North Korea to halt its 'provocative actions' and return to compliance with its international obligations.
The US Air Force B-1B Lancer bombers from Guam, along with the force's F-15C Eagle fighter escorts from Okinawa, Japan, flew in international airspace over the waters east of North Korea
North Korea forward Jong Tae-Se, dubbed the 'People's Wayne Rooney' by Asian media, scored twice for North Korea in a 2-2 draw with fellow World Cup finalists Greece in a friendly on Tuesday.
In an alarming development, North Korea on Friday cancelled all non-aggression pacts with South Korea and cut off a hotline with Seoul after the United Nations Security Council unanimously approved new sanctions on Pyongyang to punish it for its February 12 nuclear test.
Trump and Kim had their historic first meeting in Singapore last June, wherein they agreed on denuclearisation of North Korea.
North Korea has confirmed conducting its second nuclear test. The test was conducted "as part of the measures to bolster up its nuclear deterrent for self-defence in every way," CNN quoted North Korea's Korean Central News Agency as saying. South Korea has convened an emergency meeting of its national security council to discuss the implications of the nuclear test.
Tensions have dramatically risen on the Korean peninsula after North Korea early this month conducted its biggest nuclear test, which its state-run KCNA news agency described as a hydrogen bomb.
"North Korea is a criminal state. So this is another characteristic of where, rather than playing by any international rules that countries abide by, North Korea tries to steal its way forward rather than trying to do so through legal means," State Department spokesman P J Crowley said.
North Korea has abruptly cancelled United Nations Secretary General Ban Ki-moon's visit a day before he was due to arrive.
Goalkeeper Akihiro Hayashi emerged the hero by saving two spot-kicks as Japan upset defending champions South Korea 3-2 in a sudden death tie-breaker to move into the final of the AFC Youth championship.
North Korea on Wednesday test-fired a ballistic missile towards the Sea of Japan.