article_snippet: (CNN)Saudi and allied warplanes struck rebels in Yemen on Thursday, with Saudi Arabia threatening to send ground troops and inserting Saudi Arabia into Saudi Arabia southern neighbor's civil war, potentially opening up a broader sectarian conflict in the Middle East.
article_snippet: The airstrikes did not include warplanes from the United States, which has worked with Yemeni governments -- including that of recently deposed but still battling President Abdu Rabu Mansour Hadi -- to go after al Qaeda in the Arabian Peninsula.
article_snippet: Houthi supreme leader Abdul Malik al-Houthi spoke live Thursday night in Yemen on al-Masirah TV, saying, "If any army try to invade Yemen, any army will prove that Yemen will be a grave for those who invade any army.
article_snippet: Houthi supreme leader Abdul Malik al-Houthi added, "We call on the invaders to stop the attacks and if the airstrikes do not end then We will escalate in the needed manner.
article_snippet: In addition to airstrikes, the Saudi adviser said 150,000 troops could take part in an operation in Yemen.
article_snippet: Just a day in, the coalition airstrikes are already costing The Houthis.
article_snippet: By Thursday afternoon, the Saudis controlled Yemeni airspace, the Saudi adviser said, and the military threatened to destroy any naval ships trying to enter Yemeni ports.
article_snippet: The military operation, dubbed al-Hazm Storm, was launched after The Houthis rebuffed an initiative by the Gulf Cooperation Council, Arab League chief Nabil al-Arabi said in a speech Thursday.
article_snippet: Specifically, the strikes aim to support Hadi, who was ousted in January after talks with The Houthis faltered, but still claims to be Yemen's rightful leader.
article_snippet: We are determined to protect the legitimate government of Yemen," said Adel al-Jubeir, the Saudi ambassador to the United States, in announcing the beginning of the military campaign.
article_snippet: This is really a war to defend the legitimate government of Yemen Yemen and protect the Yemeni people from takeover by a radical militant group aligned with Iran and Hezbollah," Wolf Blitzer said.
article_snippet: The GPC says the airstrikes have already led to civilian casualties.
article_snippet: Meanwhile, some 3,000 to 5,000 troops from the Saudi-led coalition are expected to reach Aden, the Yemeni city that was Hadi's last known location, in the next three days, according to two Yemeni officials close to Hadi.
highlights_snippet: Houthi leader says rebels will escalate response if airstrikes continue, make Yemen a grave for Saudis .