The U.S. is the only major nation that has refused to sign the treaty, which has been endorsed by 161 countries and the European Union.

Defense Secretary Leon Panetta dismissed objections from treaty opponents who claim that it would restrict military operations or limit intelligence collection in territorial waters.

The opponents, he said, “have put forward the myth that the Law of the Sea Convention would force us to surrender U.S. sovereignty. Nothing, nothing, could be further from the truth. Not since we acquired the lands of the American West and Alaska have we had such a great opportunity to expand U.S. sovereignty.”

Panetta added that signing onto the treaty would help enforce sea lanes, including the Strait of Hormuz, which Iran has threatened to block.

“We are determined to preserve freedom of transit there in the face of Iranian threats to impose a blockade,” said Panetta, even as U.S. ships continue to travel through the Strait in part to show that the U.S. will not tolerate any effort to restrict travel there. Ratifying the treaty, Panetta added, would “help strengthen worldwide transit passage rights under international law and isolate Iran as one of the few remaining non-parties to the convention.”

Military leaders have also noted that the treaty is becoming more critical as nations compete for new shipping routes and natural resources in the Arctic, where the receding ice is opening sea lanes to more traffic.

A number of Republican senators oppose the pact.

So far, two dozen senators have signed a letter being circulated by Sen. Jim DeMint, R-S.C., vowing to oppose the treaty if it gets to the Senate for a vote.

The senators said in the letter that that “are particularly concerned that United States sovereignty could be subjugated in many areas” to an authority representing various countries. The letter is to be sent to Senate Majority Leader Harry Reid.

The Senate Foreign Relations Committee is expected to have a hearing on the matter, and Panetta is slated to testify.

Jodi Seth, spokesperson for Sen. John Kerry, the panel chairman, said Wednesday that there are many new members of the Senate.

“Reliably conservative-minded businesses and notable Republican national security experts have urged action to protect America’s interests. The unlikely allies who support the Treaty make a powerfully persuasive case,” said Seth.

The treaty regulates the ocean’s use for military, transportation and mineral extraction purposes and it recognizes sovereign rights over a country’s continental shelf out to 200 nautical miles and beyond if a country can substantiate its claims.

The Bush and Obama administrations have supported the pact, and Secretary of State Hillary Clinton has spoken several times about its importance.

Col. Thomas K. Wark, commander of the Virginia Air Guard’s 192nd Fighter Wing, said there would be no disciplinary or administrative actions taken against the pilots.

The pilots spoke out about oxygen-deficit problems with the stealth fighter, which have resulted in pilot dizziness, blackouts and other hypoxia-like symptoms.

According to the Air Force just two pilots have asked not to fly the F-22 or to be reassigned, and officials have said each pilot’s request would be handled individually.

The nation’s F-22 fighter jets were grounded for four months last year after pilots complained of experiencing a lack of oxygen that can cause dizziness and blackouts. Air Force officials said they have taken steps against the problem, but still haven’t pinpointed what’s causing the hypoxia-like symptoms. Hypoxia is when the body doesn’t receive enough oxygen.

“Though we have not yet resolved the root cause of some physiological events, we have mitigated the risk of F-22 flight operations to a level where we can safely operate the F-22 while we continue the investigation to identify the root cause,” said Lt. Col. John Dorrian on Tuesday.

Dorrian, an Air Force spokesman, said some of the measures taken to allow pilots to continue to fly the jets include an improved emergency oxygen system handle, a finger-mounted device to monitor pilot blood oxygen, and software updates to provide better oxygen sensors.

The planes are stationed at five other bases besides Virginia: Joint Base Elmendorf-Richardson, Alaska; Joint Base Pearl Harbor-Hickam, Hawaii; Nellis Air Force Base, Nev.; Holloman Air Force Base, N.M.; and Tyndall Air Force Base, Fla.

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

Gen. Liang Guanglie, China’s minister of national defense, offered a vigorous defense of his country, saying through an interpreter that, “I can hardly agree with the proposition that the cyberattacks directed to the United States are directly coming from China … We cannot attribute all of the cyberattacks (against the) United States to China.”

Just six months ago, however, senior U.S. intelligence officials for the first time publicly accused China of systematically stealing American high-tech data for its own national economic gain.

It was the most forceful and detailed airing of U.S. allegations against Beijing after years of private complaints, and it signaled the opening salvo of a broad diplomatic push to combat cyberattacks that originate in China.

Guanglie said that he and Panetta talked about ways to strengthen cybersecurity, but they are leaving the details to the experts.

Cybersecurity was just one of the many issues discussed by the two leaders during their meeting, but it is also one of a number of contentious topics that rattle the often rocky relationship between the two nations.

“The U.S. needs to start laying the ground work for better understanding by the Chinese of what we expect from them in cyberspace,” said James Lewis, a cybersecurity expert who has met with Chinese officials and scholars for informal discussions. “We want to figure out some way to get some understanding in place before something bad happens.”

As an example he said American officials want to know who to talk to when Chinese hackers breach U.S. computer networks. And if there is a cyber incident in China, Lewis said, “we need the Chinese to feel confident that they can call us up and ask, ‘was it you?’, and get a straight answer.”

Chinese officials have routinely denied the cyberspying, insisting that their own country also is a victim of such attacks. And they note that the hacking is anonymous and often difficult to track.

U.S. cybersecurity experts acknowledge that attribution can be difficult, and that while they can trace an attack to China, it is often difficult to track directly to the Chinese government. Last December’s report by U.S. intelligence agencies said America must openly confront China and Russia in a broad diplomatic push to combat cyberattacks that are on the rise and represent a “persistent threat to U.S. economic security.”

And, separately, several cybersecurity analysts have concluded that as few as 12 different Chinese groups, largely backed or directed by the government there, commit the bulk of the cyberattacks that aim to steal critical data from U.S. companies and government agencies. Officials estimate that the stealthy attacks have stolen billions of dollars in intellectual property and data.

Because people and businesses in both China and American have been victims of cyberattacks, officials have been talking more about building a better relationship so that they can work together.

Law enforcement is one area of cybersecurity where the two nations have begun to build partnerships, but so far it has been extremely limited. Lewis said that in 2011, U.S. authorities requested assistance from the Chinese 11 times, and in seven of the cases received no information. But, he said the Chinese cooperated with U.S. law enforcement in a high profile financial fraud case late last year.

“Maybe we’ve gotten overconfident and maybe we’ve gotten a little bit comfortable in our young leaders,” Gen. Ray Odierno, the Army chief of staff, told The Associated Press in an interview Thursday. “Realizing that they are young, they don’t have a lot of experiences. We have to continue to assist them so they understand what is expected of them.”

Marine Corps Commandant Gen. James Amos was blunter.

“We are allowing our standards to erode,” he wrote his commanders. “A number of recent widely publicized incidents have brought discredit on the Marine Corps and reverberated at the strategic level. The undisciplined conduct represented in these incidents threatens to overshadow all our good work and sacrifice.”

Panetta, in his first personal appeal to troops on the issue, planned to remind them that they are representing the U.S. people and that America’s greatness lies not in its ships and fighter jets, but the character and standards of its armed forces.

Senior leaders have warned for several years about a deterioration of discipline that may have contributed to increased substance abuse problems, suicides, domestic abuse and other problems.

Late last year Lt. Gen. Mark Hertling, who now commands U.S. Army Europe, suggested that while only a small percentage of soldiers lack discipline, “if you allow that to go unnoticed, it becomes cancerous.”

In January, U.S. Marines were found to have made a video showing them urinating on Afghan insurgents’ corpses. In February, troops mistakenly burned copies of the Quran, which led to violent protests and revenge killings of six Americans. In March, a U.S. soldier left his base and allegedly killed 17 civilians, mainly women and children. Last month, newly revealed photographs showed U.S. soldiers posing in 2010 with Afghan police holding the severed legs of a suicide bomber.

Gen. John Allen, the top U.S. commander in Afghanistan has expressed concern about the impact that those incidents have had on the war, according to a senior defense official. Allen believes that a number of major setbacks in the past six months have resulted from moral, not operational, failures, said the official, who spoke on condition of anonymity to discuss internal assessments.

Insurgents have used the incidents to incite violence and undermine U.S. efforts to win over the Afghan people, considered critical to counterterrorism operations. The incidents have reinforced the perception of Americans as unfriendly or occupying forces who do not understand the culture or the religion of the people they are supported to protect.

Such ethical lapses have occurred in war through the centuries. But military officials and outside experts generally agree that America’s longest war has put unprecedented strain on the country’s all-volunteer military, an overwhelmingly young force that needs supervision and strong leadership.

In earlier conflicts such as those in Vietnam or Korea, such incidents were not as readily visible. Today, they end up on YouTube in seconds, viewed by an audience that does not always attribute such behavior to the stress of war.

After writing his letter to Marine commanders, Amos began taking his message to bases and stations in talks with officers.

“I expect each of you to hold yourselves and your Marines to the highest standards … nothing else is acceptable,” he wrote in the letter.

Odierno included the topic during meetings with his two- and three-star commanders, as well as in talks with younger officers he sees during base visits.

“We’re putting a lot more responsibility on very young leaders, lieutenants and sergeants,” Odierno said. “We just have to remind everybody that we have to put the checks and balances in place, and we have to remind everybody about the importance of culture and the profession.”

He said that overall the force has behaved admirably over the past 11 years of war, and troops understand the importance of standards and discipline.

“I think it’s important for them to hear from me and other senior leaders that it’s very important to us as well,” said Odierno. “And that we have to do this together.”

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AP National Security Writer Robert Burns contributed to this report.