* U.S. pending home sales weigh on Treasuries
* Russia-Ukraine tensions cap bond yields
* U.S. 30-year bond yields rise after 4 days of losses
NEW YORK, April 28 (Reuters) - U.S. Treasury prices fell on Monday as investors felt comfortable embracing riskier assets due to gains on Wall Street and upbeat housing numbers that strengthened the view that the world's largest economy was steadily recovering.
Losses, however, remained limited by the ongoing political tension between Russia and Ukraine.
Yields on U.S. 30-year bonds rose after four days of losses. On Friday, long bond yields fell to their lowest in more than nine months after Russia unexpectedly raised interest rates just hours after the S&P downgraded the country's credit rating.
Benchmark U.S. 10-year yields also rose after three days of losses.
U.S. pending home sales for March, which rose for the first time in nine months, undermined Treasuries. The National Association of Realtors said its Pending Home Sales Index, based on contracts signed last month, grew 3.4 percent to 97.4. The increase beat economists' expectations for a 1.0 percent advance.
"Much of the data the past month has been stronger than expected and the only reason we're not seeing higher yields is because of tension in Ukraine," said David Coard, head of fixed income sales and trading, at Williams capital in New York.
"The flight-to-quality bids have definitely kept a lid on yields."
In mid-morning trading, the benchmark 10-year U.S. Treasury note was down 10/32 in price to yield 2.70 percent, up from 2.66 percent late Friday. Prices of 30-year Treasury bonds fell 26/32 to yield 3.48 percent, compared with 3.44 percent the previous session.
The five-year note, meanwhile, edged up 4/32 in price to yield 1.75 percent.
"The market generally has had a good tone the past several weeks. It's fairly healthy to see this occasional sell-off, because it does remind investors that there is some risk in owning Treasuries," said Aaron Kohli, interest rate strategist, at BNP Paribas in New York.
But he added that Treasuries have positive momentum going forward, especially in the wake of geopolitical worries involving Russia.
The United States on Monday imposed sanctions against seven Russian government officials and 17 companies linked to Russian President Vladimir Putin in its latest action to punish Moscow for its intervention in Ukraine.
The news did help Treasuries a little, but bids were short-lived, and the market was back to where it was before the new sanctions were announced.
"I think rates are having a hard time holding losses," BNP's Kohli said. "The reason for that is partly bad positioning. Others who got there early, loaded up on rates early in the year and now there's some positioning clean-up that needs to be done."
(Editing by Chizu Nomiyama)