The US Treasury has moved to support the long end of the government bond market by doubling the size of planned buybacks of longer-dated debt, seeking to ease liquidity pressures after a sharp selloff pushed the 30-year Treasury yield to its highest level since 2007, Reuters reported.Treasury will increase buybacks of 10- to 30-year Treasury securities to at least $4 billion per operation, from the previously planned $2 billion. The larger purchases will apply to the 10- to 20-year and 20- to 30-year sectors and will run from September 9 through November 4.The move came after the 30-year Treasury yield climbed to 5.34% on Tuesday, its highest level in 19 years, amid concerns over escalating tensions involving the United States, Israel and Iran and growing worries about the U.S. fiscal outlook. The yield later eased, with the 30-year yield last trading at around 5.184% following the Treasury announcement.The benchmark 10-year Treasury yield also declined on Wednesday, falling about 6 basis points to 4.66%.The Treasury said the increase in buyback sizes was aimed at providing greater liquidity to longer-dated nominal securities, where it has seen strong demand from market participants. The department has conducted scheduled purchases of older Treasury securities over the past two years to improve liquidity in less actively traded, or off-the-run, securities, Reuters reported.Focus on rising borrowing costsThe surge in Treasury yields has raised concerns across financial markets because higher government borrowing costs can also lift financing costs for households and companies. Mortgage rates and other forms of credit can remain elevated when longer-term Treasury yields rise sharply, while the federal government's interest expense also increases.Reuters reported that total U.S. public debt outstanding crossed the $40 trillion mark on Wednesday, underscoring the sensitivity of markets to rising yields and the government's growing financing requirements.The Treasury's action is intended to provide additional support to the long-duration bond market, although it does not alter the underlying fiscal deficit or the amount of debt the government needs to finance.Market participants also noted that increased purchases of longer-dated bonds could potentially be accompanied by greater issuance of shorter-term debt, including Treasury bills and securities in the five- to 10-year maturity range.Limited impact on overall debtDespite the increase in buyback sizes, the programme remains small relative to the size of the overall Treasury market. The Treasury debt market stood at about $32.2 trillion as of Monday, while outstanding 20-year and 30-year Treasury bonds totalled roughly $5.5 trillion as of July 31.The Treasury had said earlier this month that it planned to repurchase up to $69 billion of Treasury securities across maturities between August 6 and November 5. The latest increase in buyback sizes could raise the maximum amount of planned repurchases to about $83 billion.The next scheduled buyback of 20- and 30-year bonds is due on September 24, while a buyback covering 10- to 20-year securities is scheduled for September 10.The move marks another instance of Treasury Secretary Scott Bessent responding to market volatility. Bessent had also become involved in efforts to stabilise currency markets earlier this month as the Japanese yen weakened sharply against the U.S. dollar.Fiscal concerns remainWhile the announcement helped push long-term yields lower, analysts cautioned that the move does not address the broader challenges facing the U.S. bond market, including large fiscal deficits, inflation risks and the heavy volume of debt that needs to be refinanced.Reuters reported that investors nevertheless viewed the action as a signal that the Treasury is prepared to use its available tools when market conditions become disorderly.The sharp rise in long-term yields had unsettled investors globally, making the Treasury's decision closely watched beyond the U.S. bond market. With government debt continuing to expand and refinancing needs remaining substantial, the durability of the recent decline in yields will likely depend on broader fiscal, inflation and economic trends.(Disclaimer: Recommendations, suggestions, views, and opinions given by experts are their own. These do not represent the views of The Economic Times.)