Syria's armed forces have started large-scale war games, its state-run news agency says, simulating defense against outside attacks. The exercises are an apparent warning to other countries not to intervene in the uprising against President Bashar al-Assad's rule.

The exercise began Saturday with naval forces in a scenario where they repelled an attack from the sea, and will include air and ground forces over the next few days, SANA said. State TV broadcast footage of missiles being fired from launch vehicles and warships.

Some in the Syrian opposition have appealed to the West for foreign forces to step in to stop bloodshed that they say has left more than 14,000 dead since the uprising against Assad began in March 2011. So far, the West has shown little appetite to intervene militarily in the conflict.

Special U.N. envoy Kofi Annan acknowledged in an interview published Saturday that the international community's efforts to find a political solution to the escalating violence in Syria have failed.

"The evidence shows that we have not succeeded," he told the French daily Le Monde.

Annan, the special envoy for the United Nations and the Arab League, is the architect of the most prominent international plan to end the crisis in Syria.

His six-point plan was to begin with a cease-fire in mid-April between government forces and rebels seeking to topple Assad. But the truce never took hold, and now the almost 300 U.N. observers sent to monitor the cease-fire are confined to their hotels because of the escalating violence.

On Sunday, the spokesman for Annan, Ahmad Faqzi, said he has arrived in Damascus for talks with Syrian President Bashar Assad, but did not give details about his schedule.

U.S. Secretary of State Hillary Rodham Clinton said Sunday that time is running out on Syrian peace hopes and warned that the Syrian state could collapse.

Speaking in Japan, Clinton said Annan's acknowledgement that his peace plan is failing "should be a wake-up call for everyone."

She said last month was the deadliest for the Syrian people in the 16-month revolt, but added that the opposition "is getting more effective in defense of themselves and going on the offensive against the Syrian military."

Syrian Defense Minister Dawood Rajiha attended the maneuvers and praised the "exceptional performance" of the naval forces which showed "a high level of combat training and ability to defend Syria's shores against any possible aggression."

"The navy carried out the training successfully, repelling the hypothetical attack and striking at given targets with high precision," the report said.

An Iranian official also has warned of a "catastrophe" in the Middle East if no political solution is found to the 16-month crisis.

Deputy Foreign Minister Hossein Amir Abdollahian also says Syria has a strong army and is able to defend itself from attack alone without Iran's help.

Iran is Syria's closest ally and has stood by President Bashar Assad's regime through the uprising.

Abdollahian spoke at a press conference in Amman, Jordan, Sunday.

The Associated Press contributed to this report.