WASHINGTON (AP) — The top U.S. commander in the Middle East will warn Congress on Tuesday against efforts to scale back the Navy's presence in the embattled region, saying threats from Iran and elsewhere will require more ships and maritime missile defense capabilities.

Marine Gen. James Mattis, head of U.S. Central Command, also said Syria has a "substantial" chemical and biological weapons capability and thousands of shoulder-launched missiles. Until now, the U.S. military has largely declined to describe the expanse of weapons that President Bashar Assad's regime has at its disposal.

Mattis laid out his concerns in testimony prepared for Senate and House Armed Services Committee hearings this week. He and Navy Adm. William McRaven, head of U.S. Special Operations Command, are testifying before the Senate panel Tuesday. The testimony was obtained by The Associated Press.

Mattis' comments come as the Obama administration meets with Israeli leaders this week to discuss the escalating Iranian threat and the possibility of a pre-emptive strike by Israel.

Against a backdrop of roughly $500 billion in Pentagon budget cuts over the next decade, Mattis said the U.S. must use its Navy and special operations forces to maintain a smaller but still strong military presence in the Middle East as the wars in Iran and Afghanistan end.

"The stacked Iranian threats ... of ballistic missiles, long-range rockets, mines, small boats, cruise missiles and submarines demand stronger naval presence and capability to protect vital sea lines of communication," Mattis said.

At the same time, he described a deteriorating situation in Syria, fueled in part by Iran. The prospects of a civil war are rising in Syria, he said, but the "options available to address the situation are extremely challenging."

Some members of Congress have called for U.S. and international military action against the Assad regime to stem a brutal offensive against the Syrian people. But the Obama administration and other international leaders have opposed military intervention and instead have pushed instead for increased sanctions.

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U.S. officials argue that unlike the military campaign in Libya last year that ousted Moammar Gadhafi, a military campaign in Syria would be far more difficult, would not get the backing of the U.N. Security Council and would be hampered by a less coordinated opposition force.

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Lolita C. Baldor can be followed on Twitter at http://twitter.com/lbaldor