NATO is condemning Libya's use of a scud missile in its battle against rebels who are advancing toward Tripoli to oust Libyan leader Moammar Gaddafi. NATO spokeswoman Carmen Romero says the Gadhafi government''s use of the short-range ballistic missile shows that it is "desperate" as the rebels close in on the capital. In a news conference Tuesday in Brussels, Romero said many civilians could have been killed when pro-Gaddafi forces used the missile to attack Brega on Sunday. Meanwhile, Libyan rebels are capturing key towns to the south and west of Tripoli and trying to cut off supply routes to the capital in their bid to force Gaddafi from power. The rebels said they had entered a "decisive phase" and could soon liberate all of southern Libya. The rebels said they control most of Zawiya, a strategic town 50 kilometers west of Gaddafi''s power base in Tripoli. Rebel fighters entered Zawiya Saturday in their closest approach to the capital since the early weeks of the uprising.