NEW YORK (AP) — Treasurys rates moved lower on Friday, driven down by fears over Europe’s debt crisis and tensions between North and South Korea.

In a shortened trading session, the yield on the 10-year Treasury slipped to 2.87 percent, down from a 2.92 percent yield late Wednesday. Rising Treasury prices push bond yields down.

The same worries bouyed the dollar and weighed on the euro along with most of Europe’s stock markets on Friday. The dollar index, which pits the dollar against six other currencies, rose to 80, a two-month high.

After Ireland requested a bailout from the European Union earlier in the week, nervous investors have shifted their focus to the budgets of Portugal and Spain. The current worry is that both countries will need help to manage their debts.

Traders were also nervously eyeing North Korea, which warned Friday that planned military maneuvers by South Korea and the U.S. have put the Korean peninsula on the brink of war. North Korea fired artillery shells at a South Korean island on Tuesday, killing four people.

In times of trouble, nervous investors often turn to U.S. government bonds for a safe place to park their cash.

The yield on the 30-year bond dropped to 4.20 percent, versus 4.28 percent Wednesday. The two-year note’s yield also edged lower to 0.52 percent from 0.55 percent. The U.S. bond market was closed Thursday for the Thanksgiving holiday.

In the Treasury bill market, the three-month T-bill paid a 0.15 percent yield. Its discount was 0.16 percent.