The United States Thursday implicitly reserved the right to strike Syria, alone, in its own national interest, without waiting for allies to join an operation or for global approval.

The White House said President Barack Obama prized the United Nations and closely consulted allies, but that in the end, his first duty was to US national security, which he sees threatened by a Syrian chemical weapons attack.

"We certainly are interested in engaging with the global international community on this issue," said White House spokesman Josh Earnest.

"But at the same time, the president's chief accountability is to the American people that he was elected to protect.

"The president believes strongly in making the kinds of decisions and taking the kinds of steps that are necessary to protect our core national security interests that we've acknowledged are at stake in this situation."

The comments came as Britain, Washington's closest European ally struggles for a political consensus over Prime Minister David Cameron's plans to join expected US-led military action in Syria.

The political fracas in London has sparked speculation that a timetable for action, which many observers believe could see air strikes in Syria within days, could slip.

But at the State Department, spokeswoman Marie Harf said that "we make our own decisions in our own timeline," though styled international consultations on Syria as "incredibly important."

The Obama administration also hinted that unlike Britain, it did not see the need to wait for a report by UN inspectors in Syria on the chemical attack on a Damascus suburb on August 21.

"It's not within the mandate of those UN inspectors to assess the responsibility for the use of those weapons -- it's just within their mandate to assess whether or not they were used," Earnest said.

"That's no longer an open question."

On Wednesday, the Obama administration said that it did not see any future in a British bid to secure a mandate from the UN Security Council for attacking Syria, due to Russian opposition.

Administration officials have said that Obama sees perils for US national security in the belief that Syria shattered international norms by using chemical weapons, and that US interests and allies could be threatened.

"The Syrian regime's use of chemical weapons against their own people presents a situation where, yes, US national security interests are threatened," said Harf.

US officials are concerned that the Syria's chemical weapons stocks, as well as being used by civilians, could eventually fall into the hands of terror groups or radicals opposed to the United States.

US sends fifth destroyer to eastern Med: official
Washington (AFP) Aug 29, 2013 - The US Navy has deployed a fifth destroyer to the eastern Mediterranean, a defense official told AFP on Thursday, as expectations grow of an imminent strike on Syria.

The USS Stout, a guided missile destroyer, is "in the Mediterranean, heading and moving east" to relieve the Mahan, said the official, who said both ships might remain in place for the time being.

Other destroyers in the region -- the Ramage, the Barry and the Gravely -- criss-cross the Mediterranean and could launch their Tomahawk missiles toward Syria if so directed by US President Barack Obama.

The defense official, speaking on condition of anonymity, did not say how long the Mahan would stay in the area before returning to its home port of Norfolk, Virginia, which it left in December 2012.

It is normal for three destroyers to patrol the Mediterranean under the authority of the US Sixth Fleet, primarily in an anti-missile defense role.

The US Navy keeps as a closely guarded secret the number of Tomahawk missiles that each ship carries but it is estimated to be 45.

The US defense official also indicated that the aircraft carrier USS Nimitz and its escorts remain in the area of the US Fifth Fleet, which extends from the Red Sea to the Gulf and Arabian Sea.

Defense Secretary Chuck Hagel, currently on a week-long trip to Southeast Asia, told the BBC that US forces were in place and "ready to go" if Obama gives the order but no such decision has yet been made.

A second defense official, however, said that while the Nimitz is being held, such a move should not not be linked to potential Syria options at this time.

Syria came up in a meeting between Hagel and South Korean Defense Minister Kim Kwan-Jin, with both men voicing grave concern about the use of chemical weapons, a US defense official told reporters.

Hagel told Kim that gross violations of international law cannot go "unanswered", the official said.