But Welsh First Minister Mark Drakeford told Sky News’s Sophy Ridge On Sunday programme that the decision could be reversed if “things were to go against us”.
Mr Drakeford said: “The advice to us from our chief medical officer and scientists is that you should, in these early stages, always take measures that could be reversed quickly if you needed to do that.
“If there were to be unintended consequences of having three to seven-year-olds back into school, then, of course, we would be able to go into reverse.”
He said Wales was in a position to allow the youngest children back into school as a result of its national lockdown which began shortly before Christmas.
But he stressed that return was a “tentative” first step, which would be closely monitored.
Mr Drakeford added: “We want this to be the first step on the journey to getting more children back into the classroom.
“But if things were to go against us, if a new variant were to appear for example, then we could go back to the position we are in today.”
Plaid Cymru’s leader Adam Price, meanwhile, said Covid-19 cases should be reduced even further before lockdown is lifted as another wave would be “disastrous” for the economy.
He told BBC’s Andrew Marr Show: “Now is the time to ensure we have steady progress and avoid the possibility of a third or fourth wave, which would be not just disastrous in terms of public health, but also in terms of economy.
“Because it is that ‘stop, go’ cycle of lockdown, then release, then lockdown again, which has led to great uncertainty in economic terms and we should avoid that at all costs.
“So let’s drive down the level of cases even further.”