"[If] the Americans join in, there will be peace," Lukashenko said during a speech in the parliament.
The Belarusian leader added he did not know which goals Washington was pursuing, but did not rule out that the conflict that has claimed 6,000 lives in over a year may be playing out to its advantage.
"If the US' goal is to normalize the situation in southeast Ukraine, it would be normalized 100 percent. Everyone understands this," Lukashenko said.
The US is not part of the so-called Normandy Format that signed a 13-point agreement in Minsk to alleviate a crisis that flared up early this year and most recently again over the weekend, according to the OSCE Monitoring Mission.
Russian Foreign Minister Sergei Lavrov welcomed Washington's inclusion to the Normandy Four earlier.
As part of the February 12 Minsk accords, Kiev has been struggling to carry out a series of constitutional reforms by the end of 2015 in addition to both sides observing a ceasefire, heavy arms withdrawal and prisoner exchanges.