What was shaping up to be a strong opening for U.S. stocks is less so after President Trump clarified his latest thoughts on tariffs.In a post on his Truth Social complaining about the influx of drugs from both north and south of the U.S. border, the president said tariffs will begin against Mexico and Canada on March 4 (next Tuesday). An additional 10% tariff on China will also be implemented that day, he continued.Comments Trump made at a cabinet meeting yesterday implied these tariffs weren't to begin until April.Ahead more than 1% prior to the latest threat, Nasdaq 100 futures have trimmed those gains to about 0.6%. S&P 500 futures are posting only marginal gains at press time and Dow futures have turned lower.The U.S. dollar index has shot higher by 0.5% on the news.Already under plenty of water over the past days and weeks — including a sizable tumble on yesterday's tariff chatter — crypto is more or less hanging steady at low levels following the news. Bitcoin (BTC) is little-changed over the past hour at $85,600.