However, Biden said the weapon was probably not fired by Russia, although the investigation was ongoing.
According to U.S. officials, initial findings suggested that the missile that hit Poland had been fired by Ukrainian forces at an incoming Russian missile, the Associated Press said.
"Right now, it's a bit of a tussle in the market as to how to price this risk," he added.
Risk-sensitive Antipodean currencies recovered from earlier declines with Australian dollar last up 0.19% at $0.67685, while the kiwi was flat at $0.6158.
"The currency market is stabilising, toying with the notion that this ... doesn't necessarily imply an escalation in the war, with NATO needing to get involved," said Rodrigo Catril, a senior currency strategist at National Australia Bank.