The dollar rose to a one-week high against the yen on Monday, climbing almost 2 percent, following Japanese Prime Minister Shinzo Abe's call for a fresh round of fiscal stimulus after a victory for his ruling coalition in local elections.
News that the stimulus could reach 10 trillion yen ($97.5 billion) helped Japan's stock market jump 4 percent and sent the dollar soaring against the Japanese currency. The Bank of Japan is expected to provide additional easing to keep interest rates low and the yen weak to make sure stimulus spending can gain traction.
"It now looks like there's co-ordinated fiscal and monetary policy," said Greg Anderson, global head of foreign exchange strategy at BMO Capital Markets in New York. "If you get a fiscal policy that is expansive ... the natural thing is to finance that with money-printing."
Investors had been buying the yen through much of this year as the Bank of Japan chose to hold off on currency intervention. Abe has promised to revive the economy with hyper-easy monetary policy, fiscal spending and reforms, a collective program known as "Abenonics."
The dollar rose as much as 2.1 percent to a high of 102.66 yen, on pace for its biggest one-day gain since April. It was last up 1.9 percent at 102.48 yen.
The greenback fell as low as 99 yen on June 24 in the aftermath of Britain's decision to leave the European Union, which drove investors to the Japanese currency and other safe havens.
The dollar hit a four-month high of 96.793 against a basket of major currencies, having already received a lift by a US jobs report that outpaced even the loftiest expectations on Friday. The report pushed investors to price back in the chance of an increase in interest rates by the Federal Reserve before the end of the year.
The dollar index was last up 0.2 percent at 96.501.