By James Ramage

The yen rose against the dollar, euro and British pound on Thursday after an escalation of the conflict between Ukraine and Russia sent investors scurrying into haven assets.

The dollar fell 0.2% versus the yen to Y103.66, while the euro dropped 0.3% to Y136.67. The pound slid 0.2% to Y172.

Investors moved into the Japanese currency, U.S. Treasurys and gold after Ukraine accused Russia of invading the country, renewing concerns that the conflict could destabilize eastern Europe. The worries about the stepped-up hostilities overrode the positive effect of strong U.S. economic growth for the dollar.

"Geopolitics is diverting our attention away from the economic data in the U.S.," said Vassili Serebriakov, currency strategist at BNP Paribas. "Despite the fact that the numbers were all firmer than expected, we're seeing downward pressure on U.S. yields, which weighed on dollar-yen."

An updated estimate for second-quarter gross domestic product showed the U.S. economy grew 4.2%, above forecasts for 3.8% growth. In addition, weekly U.S. jobless claims fell by 1,000 to 298,000, just below expectations of 300,000.

The news gave the dollar a small but temporary boost against the yen and the euro.

The rush to buy Treasury bonds sent yields close to their lowest point in more than a year, as bond prices and yields move inversely. This pushed the dollar lower against its rivals, as lower interest rates reduce investor returns on dollar-denominated assets.

Still, the dollar would likely regain ground if the Ukrainian conflict simmers down, Mr. Serebriakov said. The U.S. recovery appears to be gaining momentum, an important factor for the Federal Reserve's timeline for raising interest rates.

At the same time, inflation in the euro zone remains soft. The euro bloc will see consumer price data Friday, which is expected to show little change from recent numbers that have been well below the European Central Bank's 2% target, pressuring the central bank to introduce new easing measures at its policy meeting next week.

The euro slipped 0.1% against the dollar Thursday, to $1.3185.

-Write to James Ramage at james.ramage@wsj.com