By Ruth Carson and Alice Atkins

(Bloomberg) -- Treasuries fell, pushing yields to the highest in more than four months as a fierce selloff in Japanese bonds spilled over into global debt markets.

Longer maturities led losses, with US 30-year yields rising nine basis points to 4.93% and 10-year yields up seven basis points to 4.29%, the highest levels since Sept. 3.

Most Read from Bloomberg

• Seattle Is Building Light Rail Like It’s 1999

• Chicago Splits 2026 Advance Pension Payment on Cash Crunch

Trading of the securities resumed following a US holiday on Monday, with investors reacting to a tumble in Japanese bonds, as well as rising tensions between Europe and the US over control of Greenland.

Concern around Japan’s fiscal outlook sent yields on the nation’s 40-year debt rocketing above 4% in the Asian session, the most on record. That’s weighing on long-dated debt around the world, with 30-year bonds also underperforming in Europe.

“Yields on JGBs have reached levels that make investing in US Treasuries unattractive on a currency-hedged basis,” said Ronald Temple, chief market strategist at Lazard Asset Management. “If JGB yields continue to rise, a rational choice by Japanese investors could be to move capital back to Japan.”

Traders are also catching up to the escalation of President Donald Trump’s threats over Greenland. His plan to impose new levies on selected European nations as part of a bid to take control of the territory has revived questions about the unpredictability of his policies and the desirability of US investments.

The escalating transatlantic rift has fueled debate about whether European countries will weaponize their holdings of US bonds and stocks, potentially driving borrowing costs up and equities down given US reliance on foreign capital.

“The key new dynamic now is that the US has become the source of uncertainty, not the safe haven from it,” said Andrew Ticehurst, senior rates strategist at Nomura Australia Ltd. in Sydney.

By one metric, long-dated Treasuries are set to cheapen the most in a day since May. The gap between 30-year yields and equivalent interest-rate swaps widened three basis points to 68. Still, that’s some way below the levels seen following Liberation Day in April, when momentum to sell US assets surged and the so-called swap spread widened to one-percentage point.