The Pentagon made that assertion in a letter to lawmakers who wanted to know about the logistics and human cost of any conflict with North Korea.
Rear Adm Michael J Dumont of the Joint Staff offered the assessment in response to a letter from Reps Ted Lieu of California and Ruben Gallego of Arizona.
"Their assessment underscores what we've known all along: there are no good military options for North Korea", the statement said.
Potential casualties from a conflict depended heavily on the intensity of any attack on South Korea's capital, Seoul, which lies just 35 miles (56 km) from the border, as well as how much advance warning the U.S. and its allies had, he said.
The risks involved included a potential nuclear counter-attack by North Korea while USA forces attempted to disable its "deeply buried, underground facilities", he said.
The Pentagon declined to detail how the US would counter a nuclear strike by North Korea, but offered to give lawmakers a classified briefing on the matter.
The lawmakers said a ground invasion would be "deeply disturbing" and warned it "could result in hundreds of thousands, or even millions of deaths in just the first few days of fighting".
While an estimated 29,000 U.S. troops are deployed in South Korea, "It's important for people to understand what a war with a nuclear power would look like", said Lieu, who pointed to estimates of at least 300,000 dead on both sides within just the first few days.
In terms of providing humanitarian assistance during or after conflict, Dumont said South Korea will have the primary responsibility for "post-conflict and transitional operations" on the Korean Peninsula.
'With that in mind, the thought of sending troops into harm's way and expending resources on another potentially unwinnable war is chilling.
Iranians hold rallies to mark US Embassy takeover
The former USA embassy in Tehran is now a cultural centre but stands as a symbol of a United States defeat for many Iranians. The US cut its diplomatic relations with Iran following the embassy takeover and has had no diplomatic relations since.
CNN reports North Korean government officials saying that the nation is watching Trump's Asia visit closely and is monitoring the three carrier strike groups off South Korea. He also singled out trade, which he said had been "badly handled" in the region for years. The situation worsened when Trump, during his first address to the United Nations General Assembly (UNGA), vowed to annihilate North Korea if it posed any threat to the U.S. and its allies, and called the Pyongyang leader "rocket man" on a suicide mission. In a speech before US troops based in Japan, Trump claimed that "no dictator, no regime and no nation, should underestimate, ever, American resolve". The U.S. administration says it seeks a diplomatic solution to the nuclear standoff but "all options" are on the table. It was not pleasant for them, was it?' said Trump, who wore a leather bomber jacket as he addressed the troops.
North Korea has continued to test nuclear weapons and ballistic missiles, despite several sanctions imposed on the country by the United Nations.
'We will never yield, never waver and never falter in defense of our freedom, ' Trump said.
The "vicinity" just happened to be near North Korea.
He also gave some detail on what the first hours of a war would involve. It's a big problem for our country and the world, and we want to get it solved, ' he said.
A Congressional Research Service report published last week said that conservative estimates anticipate that in the first hours of a conflict, North Korean artillery situated along the frontier could cause tens of thousands of casualties in South Korea, where at least 100,000 and possibly as many as 500,000 Americans live - including almost 30,000 US troops.
Democratic Sen. Tammy Duckworth of IL wrote to Trump Wednesday calling for him to provide the American public with declassified estimates of potential casualties, costs and outcomes from a limited or full-scale war with North Korea.
Beijing has pleaded with both the U.S. and Pyongyang to 'realize that resorting to military force will never be a viable way to resolve the peninsula issue and their own concerns, adding that 'War on the peninsula will have no victor'.
The bill targets banks and other financial institutions that continue to do business with Pyongyang and anyone else that evades existing sanctions to support with the rogue nation.
The Giants also waived defensive end Jordan Williams and corner Tim Scott - both of whom played in Sunday's loss. Jenkins was late returning to the team after the bye week, missing a day with an unexcused absence.
Nakagawa rejected defence lawyers' arguments that Kakehi was not criminally liable because she was suffering from dementia. The court underlined that Kakehi did not suffer dementia when she committed the last crime in December 2013.
Bradford, who has missed six of the past seven games, would be done for the regular season if placed on injured reserve. The Vikings then traded for Bradford, who led the team to an 8-8 record during the 2016 season.
Perhaps the most important new news on the bid is that Qualcomm is expected to reject this deal as it undervalues the company. The company has also got commitment letter for $5 billion debt financing from private equity Silver Lake Partners.
The moment surprised the crowd at the glitzy gala, which was held at the Beverly Hilton Hotel in Beverly Hills. Watch the amusing interaction below! It's a case of ask and you shall receive in the world of Kate Winslet .
It will then come to Google Maps to Android, at which point it will expand to include grocery stores, the company says. Search for a restaurant using Google, and you're already told the times of day at which a particular place is busiest.
The relatively easy-going driving conditions and lax regulatory environment have made it a great testing ground for Waymo. There's also an onboard support system that allows them to talk to a live Waymo support agent at any time.
So it would definitely be interesting to see how a more-focused-on sports Fox would do, and how investors would react. Disney already owns ABC , and therefore can not also own another broadcast network, due to FCC regulations.
Mike Evans suspended for hit on Marshon Lattimore
The hit, which Evans called "unprofessional", occurred in the third quarter of the Saints' 30-10 win against the Buccaneers. Evans drilled Saints cornerback Marshon Lattimore after Lattimore pushed Jameis Winston , who poked him in the head.