JERUSALEM — Israel announced plans on Sunday to boost its Iron Dome missile interceptor system, citing successful tests of the largely U.S.-funded system conducted in light of what it called "a variety of unprecedented threats."

A Defense Ministry statement said a fifth battery of the rockets, used so far to fend off salvos fired by Palestinian militants in the Gaza Strip, would be added to the system "within a short time" following successful tests of an upgrade.

Tests were carried out on the system "to improve its performance and capabilities of the system against a variety of unprecedented threats," the statement said.

Urgent Poll: Romney or Obama to Handle Foreign Crisis? Vote Here!

It was not immediately clear exactly where the new unit would be deployed. A senior Israeli official suggested in a briefing to reporters in April there were thoughts of placing another battery in the greater Tel Aviv area.

Since early 2011, Israel has deployed several Iron Dome batteries in its southern region. The system uses small radar-guided missiles to blow up Katyusha-style rockets with ranges of between 5 km (3 miles) and 70 km (45 miles), and mortar bombs, in mid-air.

Israel has also developed a longer-range interceptor, called Arrow, to defend against possible missile strikes from Iran.

Israel has not ruled out military action to prevent Iran from building a nuclear weapon. Tehran denies seeking such weaponry.

The U.S. Congress approved $205 million for Iron Dome in fiscal 2011. The units are estimated to cost about $50 million each.