South Korea may have secretly transferred "hundreds of thousands" of artillery rounds for Ukraine under an agreement with the United States, the Wall Street Journal reported, citing US officials.

Under the confidential arrangement, South Korea is transferring the shells to the US, which in turn has arranged for them to be sent to Ukraine, per the WSJ report.

"The decision marks a turnabout by Seoul, which had pledged the artillery in November but then baulked at providing lethal assistance, following months of US pleas for help as the Pentagon’s own supply of artillery dwindles," it writes.

While the Pentagon declined to say how the shells are being sent or when the transfer is to be completed, it acknowledged that it has been in discussion with Seoul on buying its ammunition.

The agreement was discussed between Washington and Seoul last year, but was delayed when the details were leaked to the press, US officials told the Wall Street Journal.

South Korea’s contribution of rounds has enabled the Biden administration to delay for now a decision on whether to send cluster munitions to the Ukrainians, a move that Kyiv has been lobbying for a long time ahead of an anticipated counteroffensive.