* U.S. officials set aggressive tone on America First
* Deliver riposte to concerns about protectionism
* Say more America First steps to come
* Ross sees "inappropriate behaviour" by trade partners (Adds White House comment in paragraphs 7-8)
By Paritosh Bansal, Noah Barkin and Yara Bayoumy
DAVOS, Switzerland, Jan 24 (Reuters) - U.S. Treasury Secretary Steven Mnuchin welcomed a weaker dollar on Wednesday, sending the greenback reeling and underlining concerns that U.S. President Donald Trump is stepping up his attack on China and other big trading partners as part of his America First agenda. Mnuchin made the remark, seen by markets as a departure from traditional U.S. currency policy, at the World Economic Forum in Davos, where other world leaders have made swipes at what they see as U.S. protectionism.
Tough U.S. talk on trade, on the eve of Trump's arrival at the Swiss ski resort on Thursday, contrasted sharply with a chorus of government leaders, from India and Brazil to Germany and Canada, who urged cooperation and criticised protectionism.
"Obviously a weaker dollar is good for us as it relates to trade and opportunities," Mnuchin told a press briefing.
Commerce Secretary Wilbur Ross later told CNBC that his colleague was "not advocating for a weaker dollar", but he also struck a combative tone.
Asked if he was concerned about sparking a trade war, Ross said: "Trade war has been in place for quite a little while, the difference is the U.S. troops are now coming to the ramparts.”
Pressed about Mnuchin's remarks, White House spokeswoman Sarah Sanders said at a daily briefing in Washington: "We believe in a free-floating currency. The president has always believed in that."
"We have ... a very stable dollar, in large part due to how well the U.S. economy is doing right now," she added.
The annual Davos gathering of world leaders, chief executives and non-governmental agencies has long embraced globalisation, free trade and liberal values.
Trump, the first sitting U.S. president to attend the forum since Bill Clinton in 2000, has questioned that world view. He has threatened to withdraw from the North American Free Trade Agreement (NAFTA), disavowed the global climate change accord and criticised institutions such as the United Nations and NATO.
With Trump expected to address the summit on Friday, world leaders here have raised concerns about a return to greater economic protectionism.
Italian Prime Minister Paolo Gentiloni, asked what his message to Trump was, offered a defence of multilateral cooperation and warned against undermining that.
Germany's Angela Merkel, in an address to the forum, evoked the two World Wars and questioned whether the world had learned from them.
French President Emmanuel Macron opened his well-attended speech by joking that the conference "obviously and fortunately didn't invite anyone sceptical" about global warming.
Indian Prime Minister Narendra Modi, Canada's Justin Trudeau and Brazilian President Michel Temer have also embraced the idea of globalisation and cooperation.
Mnuchin defended Trump's agenda.
"This is about an America First agenda. But America First does mean working with the rest of the world," Mnuchin said. "It just means that President Trump is looking out for American workers and American interests no different than he expects other leaders would look out for their own."
Ross said U.S. trade actions were provoked by "inappropriate behaviour on the part of our trading counterparties".
On Tuesday, the United States slapped steep import tariffs on washing machines and solar panels, moves billed as a way to protect American jobs. China and South Korea condemned the tariffs, with Seoul set to complain to the World Trade Organization over the "excessive" move.
"Many countries are very good at the rhetoric of free trade but in fact actually practice extreme protectionism," Ross said.
The Commerce Secretary also said U.S. trade authorities are investigating whether there is a case for taking action against China for infringing intellectual property, calling Beijing's 2025 technology strategy a threat.
A slide in the U.S. dollar should help U.S. exporters, but Mnuchin also added a nuanced outlook: "Longer term, the strength of the dollar is a reflection of the strength of the U.S. economy and the fact that it is and it continues to be the primary currency in terms of the reserve currency."
The U.S. delegation is the largest ever to come to Davos, with 10 members of Trump's cabinet and senior White House staff, Mnuchin said. Delegates include Jared Kushner, Trump's son-in-law and adviser.
Mnuchin said American involvement in a new Asia-Pacific trade pact between 11 countries was "not off the table", despite Washington pulling out of early talks on the deal last year.
But he added, "We are fans of bilateral trading agreements."
Earlier on Tuesday, Canada's Trudeau called the new trade agreement, expected to be signed in Chile in March, the "right deal".
Ross said Trudeau's comments needed to be taken in the context of the latest round of talks on NAFTA. Perhaps there was some inclination to use that to "put pressure on the U.S. in the NAFTA talks," Ross said. (Reporting by Paritosh Bansal, Noah Barkin and Yara Bayoumy; Additional reporting by Roberta Rampton in Washington, Editing by William Maclean, Simon Robinson, Peter Graff and Chizu Nomiyama)