New York, March 7(AFP/APP):The question marks hanging over US President Donald Trump's aggressive trade agenda kept world markets guessing on Tuesday, with stocks managing to end mostly firmer.

Wall Street eked out a positive finish after repeatedly bouncing in and out of negative territory on persistent trade worries.

Earlier, European and Asian stocks consolidated gains made after following New York's lead from Monday's higher close, when investors had cast off trade fears to recover some of the losses from last week.

Trump's sudden threats to slap tariffs on all steel and aluminum imports sparked a global sell off, but comments indicating Canada and Mexico might eventually be exempt calmed some of the concerns.

The Dow squeaked into positive territory in the final minutes while the Nasdaq added 0.6 percent.

“A lot of nervousness, a lot of uncertainty coming out of Washington and investors are not sure of what that means, whether it will it be limited or the ramifications have broader impact,” Adam Sarhan of Park 50 investments told AFP.

Republican congressional leaders emphasized their opposition to the possible tariffs, which could be announced in the coming days, and US trading partners continue to threaten retaliation, including Mexico and the European Union.

Markets also were buoyed by an announcement from Seoul that the leaders of North and South Korea will hold a historic summit next month after Pyongyang expressed willingness to discuss giving up its nuclear weapons.