Saudi Arabia on Thursday beefed up security measures along its borders and on key sites, including oil installations, as it launched a military campaign against the Iran-backed Shiite Houthi rebels in Yemen, the interior minister said.

Prince Mohammed bin Nayef vowed that the kingdom will “act firmly” against any attempts to undermine Saudi Arabia’s security, the Saudi Press Agency (SPA) reported.

The statement came after Prince Nayef chaired a meeting of security chiefs to discuss “developments in light of the military operations” in Yemen and “security measures needed to face them,” SPA reported.

Prince Nayef ordered the “strengthening of all security measures along the kingdom's borders and at all public, oil and industrial facilities.”

Saudi Arabia is the world's top oil exporter and has borders with Yemen, where its warplanes began an offensive overnight against the Shiite Houthi rebels, backed by Iran which lies just across the Gulf.

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Riyadh is also taking part in the U.S.-led coalition carrying out strikes against the Islamic State of Iraq and Syria (ISIS) group, which has seized territories in Syria and Iraq.

The kingdom on Thursday halted flights at seven airports near the Yemeni border and declared the Yemeni airspace a “restricted area.”

Overnight strikes by the Royal Saudi Air Force targeted Houthi air defenses and military bases. A key air base that the militia uses in Sanaa was destroyed, Al Arabiya News Channel reported.

[With AP]