(Reuters) -U.S. President Donald Trump said on Monday that a "complete and total" ceasefire between Israel and Iran will go into force with a view to ending the conflict between the two nations.

"On the assumption that everything works as it should, which it will, I would like to congratulate both Countries, Israel and Iran, on having the Stamina, Courage, and Intelligence to end, what should be called, 'THE 12 DAY WAR'," Trump wrote on his Truth Social site.

U.S. crude futures tumbled after Trump's announcement, which came after the close of trading on Wall Street. S&P 500 e-mini futures rose when trading resumed, while the U.S. dollar fell.

COMMENTS

HIROFUMI SUZUKI, CHIEF FX STRATEGIST, SMBC, TOKYO:

"Following President Trump's ceasefire announcement, financial markets, including the crude oil market, have returned to levels seen before the tensions between Israel and Iran began. This is also true for the USD/JPY exchange rate, as the dollar buying driven by the worsening Middle East situation seems to have dissipated.

"Going forward, it will depend on how feasible both Iran and Israel find the ceasefire to be. If the ceasefire proceeds as announced, the USD/JPY may gradually move back towards yen appreciation."

TONY SYCAMORE, MARKET ANALYST, IG, SYDNEY:

"There's a high chance that we've seen the end of the conflict for now. We still have some questions around where 400 kilograms of uranium have moved to, that's a massive concern still. So while I say we've got a big de-escalation, I don't think we're completely out of the woods.

"There is a lot of relief in markets, and things do look like they've de-escalated, but there's still some unanswered questions."

RAY ATTRILL, HEAD OF FX STRATEGY AT NATIONAL AUSTRALIA BANK, SYDNEY:

"There is a lot of the momentum to the reversal in the oil price strength that we are already seeing after the Iran’s strike on Qatar, which was clearly very well choreographed to be symbolic but for domestic consumption.

"To the extent that we've got a reduction in the risk of a renewed oil price spike, I think that plays positively from a risk point of view. I think it sort of removes that downside global growth risks. And I'd expect that it will supports some further, modest sort of grind higher in those sort of procyclical currencies.”

"So I think that would encourage people in the view that maybe the US dollar can sort of resume its downtrend here."

ROBERT PAVLIK, SENIOR PORTFOLIO MANAGER, DAKOTA WEALTH, NEW YORK:

"I think it's going to be huge. We could have an Iran with very limited nuclear capabilities. We can have a country that is still intact, but still the same regime, so we don't have to deal with regime change. We could have an attack on Israel certainly off the table, and we don't have any kind of threat of life to the United States troops. So the market should like that. I expect some more positive market reaction tomorrow as we go forward."

ART HOGAN, CHIEF MARKET STRATEGIST, B. RILEY WEALTH, NEW YORK:

"If, in fact, this holds, I would certainly say that's a market positive, and the futures are leaning in that direction."

"Talk is cheap around these types of things. But certainly, I think the market and the rest of the world would like to see this come to some sort of peaceful resolve and not escalate further than what we've seen already. And I think that this afternoon's market action was leaning in that direction, and hopefully this is the next step in that direction, such that we don't have to worry about the next level of escalation, which is never going to be pretty."

JACK ABLIN, CHIEF INVESTMENT OFFICER, CRESSET WEALTH ADVISORS, PALM BEACH, FLORIDA:

"This lifts some of the geopolitical uncertainty surrounding the markets, although, for the most part, equity investors have been kind of shrugging the uncertainty off. I think it's certainly an incremental positive, but I don't think it's a catalyst for the next bull market."

"It certainly sounds like a significant milestone, and I hope it it's true."

JAKE DOLLARHIDE, CEO, LONGBOW ASSET MANAGEMENT, TULSA, OKLAHOMA:

"Part of the problem holding equities back has been higher oil prices and geopolitical risk, and a cease fire or end to the conflict would go a long way towards solving both those issues." 

"This may be the match that sparks a continuation of the rally we saw today."

(Compiled by the Global Finance & Markets Breaking News team)